diff --git a/mindspore/offline_debug/debugger_tensor.py b/mindspore/offline_debug/debugger_tensor.py
new file mode 100644
index 00000000000..1edec4651e2
--- /dev/null
+++ b/mindspore/offline_debug/debugger_tensor.py
@@ -0,0 +1,92 @@
+# Copyright 2021 Huawei Technologies Co., Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""DebuggerTensor."""
+from abc import ABC
+
+
+class DebuggerTensor(ABC):
+    """
+    The tensor with specific rank, iteration and debugging info.
+
+    Note:
+        - Users should not instantiate this class manually.
+        - The instances of this class is immutable.
+        - A DebuggerTensor is always the output tensor of a node.
+    """
+    @property
+    def node(self):
+        """
+        Get the node that outputs this tensor.
+
+        Returns:
+            Node, the node that outputs this tensor.
+        """
+        return None
+
+    @property
+    def name(self):
+        """
+        Get the name of this tensor.
+
+        The name is composed of full name of a node and the slot number.
+
+        Returns:
+            str, the name of this tensor.
+        """
+        return ""
+
+    @property
+    def slot(self):
+        """
+        Get slot.
+
+        Returns:
+            int, the slot of the tensor on the node.
+        """
+        return -1
+
+    @property
+    def iteration(self):
+        """
+        Get the iteration for this tensor.
+
+        Returns:
+            int, the iteration for this tensor.
+        """
+        return -1
+
+    @property
+    def rank(self):
+        """
+        Get the rank for this tensor.
+
+        Returns:
+            int, the rank for this tensor.
+
+        """
+        return -1
+
+    def get_value(self):
+        """
+        Get the value of the tensor.
+
+        Returns:
+            numpy.ndarray, the value of the debugger tensor.
+        """
+
+    def get_affected_nodes(self):
+        """
+        Get the nodes that use current tensor as input.
+        """
diff --git a/mindspore/offline_debug/dump_analyzer.py b/mindspore/offline_debug/dump_analyzer.py
new file mode 100644
index 00000000000..1015bd57e7b
--- /dev/null
+++ b/mindspore/offline_debug/dump_analyzer.py
@@ -0,0 +1,138 @@
+# Copyright 2021 Huawei Technologies Co., Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Debugger python API."""
+
+from typing import Iterable
+
+from mindspore.offline_debug.debugger_tensor import DebuggerTensor
+from mindspore.offline_debug.node import Node
+from mindspore.offline_debug.watchpoints import WatchpointBase, WatchpointHit
+
+
+class DumpAnalyzer:
+    """
+    Analyzer to inspect the dump data.
+
+    Args:
+        summary_dir (str): The path of the summary directory which contains
+            dump folder.
+        mem_limit (int, optional): The memory limit for this debugger session in
+            MB. Default: None, which means no limit.
+    """
+
+    def __init__(self, summary_dir, mem_limit=None):
+        self._summary_dir = summary_dir
+        self._mem_limit = mem_limit
+
+    def export_graphs(self, output_dir=None):
+        """
+        Export the computational graph(s) in xlsx file(s) to the output_dir.
+
+        The file(s) will contain the stack info of graph nodes.
+
+        Args:
+            output_dir (str, optional): Output directory to save the file.
+                Default: None, which means to use the current working directory.
+
+        Returns:
+            str. The path of the generated file.
+        """
+
+    def select_nodes(
+            self,
+            query_string,
+            use_regex=False,
+            match_target="name",
+            case_sensitive=True) -> Iterable[Node]:
+        """
+        Select nodes.
+
+        Args:
+            query_string (str): Query string. For a node to be selected, the
+                match target field must contains or matches the query string.
+            use_regex (bool): Indicates whether query is a regex. Default: False.
+            match_target (str, optional): The field to search when selecting
+                nodes. Available values are "name", "stack".
+                "name" means to search the name of the nodes in the
+                graph. "stack" means the stack info of
+                the node. Default: "name".
+            case_sensitive (bool, optional): Whether case-sensitive when
+                selecting tensors. Default: True.
+
+        Returns:
+            Iterable[Node], the matched nodes.
+        """
+
+    def select_tensors(
+            self,
+            query_string,
+            use_regex=False,
+            match_target="name",
+            iterations=None,
+            ranks=None,
+            slots=None,
+            case_sensitive=True) -> Iterable[DebuggerTensor]:
+        """
+        Select tensors.
+
+        Args:
+            query_string (str): Query string. For a tensor to be selected, the
+                match target field must contains or matches the query string.
+            use_regex (bool): Indicates whether query is a regex. Default: False.
+            match_target (str, optional): The field to search when selecting
+                tensors. Available values are "name", "stack".
+                "name" means to search the name of the tensors in the
+                graph. "name" is composed of graph node's full_name
+                and the tensor's slot number. "stack" means the stack info of
+                the node that outputs this tensor. Default: "name".
+            iterations (list[int], optional): The iterations to select. Default:
+                None, which means all iterations will be selected.
+            ranks (list(int], optional): The ranks to select. Default: None,
+                which means all ranks will be selected.
+            slots (list[int], optional): The slot of the selected tensor.
+                Default: None, which means all slots will be selected.
+            case_sensitive (bool, optional): Whether case-sensitive when
+                selecting tensors. Default: True.
+
+        Returns:
+          Iterable[DebuggerTensor], the matched tensors.
+        """
+
+    def get_iterations(self) -> Iterable[int]:
+        """Get the available iterations this run."""
+
+    def get_ranks(self) -> Iterable[int]:
+        """Get the available ranks in this run."""
+
+    def check_watchpoints(
+            self,
+            watchpoints: Iterable[WatchpointBase]) -> Iterable[WatchpointHit]:
+        """
+        Check the given watch points on specified nodes(if available) on the
+        given iterations(if available) in a batch.
+
+        Note:
+            For speed, all watchpoints for the iteration should be given at
+            the same time to avoid reading tensors len(watchpoints) times.
+
+        Args:
+            watchpoints (Iterable[WatchpointBase]): The list of watchpoints.
+
+        Returns:
+            Iterable[WatchpointHit], the watchpoint hist list is carefully
+                sorted so that the user can see the most import hit on the
+                top of the list. When there are many many watchpoint hits,
+                we will display the list in a designed clear way.
+        """
diff --git a/mindspore/offline_debug/node.py b/mindspore/offline_debug/node.py
new file mode 100644
index 00000000000..e57b97280c8
--- /dev/null
+++ b/mindspore/offline_debug/node.py
@@ -0,0 +1,75 @@
+# Copyright 2021 Huawei Technologies Co., Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Node in the computational graph."""
+from abc import ABC
+
+
+class Node(ABC):
+    """Node in the computational graph."""
+    @property
+    def name(self):
+        """
+        Get the full name of this node.
+
+        Returns:
+            str, the full name of the node.
+        """
+        return ""
+
+    @property
+    def stack(self):
+        """Get stack info."""
+        return None
+
+    def get_input_tensors(
+            self,
+            iterations=None,
+            ranks=None,
+            slots=None):
+        """
+        Get the input tensors of the node.
+
+        Returns:
+            Iterable[DebuggerTensor], the input tensors of the node.
+        """
+
+    def get_output_tensors(
+            self,
+            iterations=None,
+            ranks=None,
+            slots=None):
+        """
+        Get the output tensors of this node.
+
+        Returns:
+            Iterable[DebuggerTensor], the output tensors of the node.
+        """
+
+    def get_input_nodes(self):
+        """
+        Get the input nodes of this node.
+
+        Returns:
+            Iterable[Node], the input nodes of this node.
+
+        """
+
+    def get_output_nodes(self):
+        """
+        Get the nodes that use the output tensors of this node.
+
+        Returns:
+            Iterable[Node], the output nodes of this node.
+        """
diff --git a/mindspore/offline_debug/watchpoints.py b/mindspore/offline_debug/watchpoints.py
new file mode 100644
index 00000000000..da4cbfc423d
--- /dev/null
+++ b/mindspore/offline_debug/watchpoints.py
@@ -0,0 +1,128 @@
+# Copyright 2021 Huawei Technologies Co., Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Watchpoints."""
+from mindspore.offline_debug.debugger_tensor import DebuggerTensor
+
+
+class WatchpointBase:
+    """
+    Base class for watchpoints.
+
+    Note:
+        - The watchpoint is bounded with tensor names.
+        - If multiple checking items is specified for one watch point instance,
+          a tensor needs to trigger all of them to trigger the watchpoint.
+    """
+    @property
+    def name(self):
+        """Get the name for the watchpoint."""
+        raise NotImplementedError
+
+    def check(self):
+        """
+        Check the watchpoint against the tensors.
+
+        Returns:
+            list[WatchpointHit], the hits of the watchpoint.
+        """
+
+
+class WatchpointHit:
+    """
+    Watchpoint hit.
+
+    Note:
+        - This class is not meant to be instantiated by user.
+        - The instances of this class is immutable.
+
+    Args:
+        tensor (DebuggerTensor): The tensor which hits the watchpoint.
+        watchpoint (WatchpointBase): The WatchPointBase object initialized with
+            user setting value.
+        watchpoint_hit_detail (WatchpointBase): The WatchPointBase object
+            initialized with actual value of the Tensor.
+        error_code: The code describing error.
+    """
+
+    def __init__(self,
+                 tensor: DebuggerTensor,
+                 watchpoint: WatchpointBase,
+                 watchpoint_hit_detail: WatchpointBase,
+                 error_code):
+        self._tensor = tensor
+        self._watchpoint = watchpoint
+        self._error_code = error_code
+        self._watchpoint_hit_detail = watchpoint_hit_detail
+
+    def __str__(self):
+        if self._error_code:
+            return f"Watchpoint {self._watchpoint.name} check failed " \
+                   f"on tensor {self._tensor.name}. " \
+                   f"Error detail: error detail."
+
+        return f"Watchpoint {self._watchpoint.name} triggered on " \
+               f"tensor {self._tensor.name}. " \
+               f"The setting for watchpoint is mean_gt=0.2, abs_mean_gt=0.3." \
+               f"The actual value of the tensor is " \
+               f"mean_gt=0.21, abs_mean_gt=0.35."
+
+    @property
+    def tensor(self) -> DebuggerTensor:
+        """Get the tensor for this watchpoint hit."""
+        return self._tensor
+
+    def get_watchpoint(self):
+        """Get the original watchpoint."""
+        return self._watchpoint
+
+    def get_hit_detail(self):
+        """Get the actual values for the thresholds in the watchpoint."""
+        return self._watchpoint_hit_detail
+
+
+class TensorTooLargeWatchpoint(WatchpointBase):
+    """
+    Tensor too large watchpoint.
+
+    When all specified checking conditions were satisfied, this watchpoint would
+    be hit after a check.
+
+    Args:
+        tensors (Iterable[DebuggerTensor]): The tensors to check.
+        abs_mean_gt (float, optional): The threshold for mean of the absolute
+            value of the tensor. When the actual value was greater than this
+            threshold, this checking condition would be satisfied.
+        max_gt (float, optional): The threshold for maximum of the tensor. When
+            the actual value was greater than this threshold, this checking
+            condition would be satisfied.
+        min_gt (float, optional): The threshold for minimum of the tensor. When
+            the actual value was greater than this threshold, this checking
+            condition would be satisfied.
+        mean_gt (float, optional): The threshold for mean of the tensor. When
+            the actual value was greater than this threshold, this checking
+            condition would be satisfied.
+    """
+
+    def __init__(self, tensors,
+                 abs_mean_gt=None, max_gt=None, min_gt=None, mean_gt=None):
+        self._tensors = tensors
+        self._abs_mean_gt = abs_mean_gt
+        self._max_gt = max_gt
+        self._min_gt = min_gt
+        self._mean_gt = mean_gt
+
+    @property
+    def name(self):
+        return "TensorTooLarge"
diff --git a/tests/st/debugger/test_debug_api.py b/tests/st/debugger/test_debug_api.py
new file mode 100644
index 00000000000..f4d67272f34
--- /dev/null
+++ b/tests/st/debugger/test_debug_api.py
@@ -0,0 +1,80 @@
+# Copyright 2021 Huawei Technologies Co., Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Test debug API."""
+import pytest
+
+from mindspore.offline_debug.dump_analyzer import DumpAnalyzer
+from mindspore.offline_debug.watchpoints import TensorTooLargeWatchpoint
+
+
+@pytest.mark.skip(reason="Feature under development.")
+def test_export_graphs():
+    """Test debug API."""
+    my_run = DumpAnalyzer(
+        summary_dir="/path/to/summary-dir1"
+    )
+
+    # Export the info about computational graph. Should support multi graphs.
+    my_run.export_graphs()
+
+
+@pytest.mark.skip(reason="Feature under development.")
+def test_select_tensors():
+    """Test debug API."""
+    my_run = DumpAnalyzer(
+        summary_dir="/path/to/summary-dir2"
+    )
+
+    # Find the interested tensors.
+    matched_tensors = my_run.select_tensors(".*conv1.*", use_regex=True)
+    assert matched_tensors == []
+
+
+@pytest.mark.skip(reason="Feature under development.")
+def test_check_watchpoints_all_iterations():
+    """Test debug API."""
+    my_run = DumpAnalyzer(
+        summary_dir="/path/to/summary-dir3"
+    )
+
+    # Checking all the iterations.
+    watchpoints = [
+        TensorTooLargeWatchpoint(
+            tensors=my_run.select_tensors(
+                "(*.weight^)|(*.bias^)", use_regex=True),
+            abs_mean_gt=0.1)
+    ]
+
+    watch_point_hits = my_run.check_watchpoints(watchpoints=watchpoints)
+    assert watch_point_hits == []
+
+
+@pytest.mark.skip(reason="Feature under development.")
+def test_check_watchpoints_one_iteration():
+    """Test debug API."""
+    my_run = DumpAnalyzer(
+        summary_dir="/path/to/summary-dir4"
+    )
+    # Checking specific iteration.
+    watchpoints = [
+        TensorTooLargeWatchpoint(
+            tensors=my_run.select_tensors(
+                "(*.weight^)|(*.bias^)", use_regex=True,
+                iterations=[1]),
+            abs_mean_gt=0.1)
+    ]
+
+    watch_point_hits = my_run.check_watchpoints(watchpoints=watchpoints)
+    assert watch_point_hits == []