diff --git a/mindspore/ccsrc/pipeline/pynative/pynative_execute.cc b/mindspore/ccsrc/pipeline/pynative/pynative_execute.cc
index c6eb673624..50684c5d54 100644
--- a/mindspore/ccsrc/pipeline/pynative/pynative_execute.cc
+++ b/mindspore/ccsrc/pipeline/pynative/pynative_execute.cc
@@ -288,6 +288,7 @@ py::object DoParamMixPrecisionCastTuple(bool *is_cast, const py::tuple tuple) {
 }
 
 bool GetSignatureType(const PrimitivePyPtr &prim, std::vector<SignatureEnumDType> *dtypes) {
+  MS_EXCEPTION_IF_NULL(dtypes);
   auto signature = prim->signatures();
   bool has_sig_dtype = false;
   (void)std::transform(signature.begin(), signature.end(), std::back_inserter(*dtypes),
@@ -733,20 +734,29 @@ ValuePtr PynativeExecutor::GetForwardValue(const OpExecInfoPtr &op_exec_info) {
 
 AnfNodePtr PynativeExecutor::MakeCNode(const OpExecInfoPtr &op_exec_info, std::vector<bool> *op_masks,
                                        abstract::AbstractBasePtrList *args_spec_list) {
+  MS_EXCEPTION_IF_NULL(op_masks);
+  MS_EXCEPTION_IF_NULL(args_spec_list);
   CNodePtr cnode = nullptr;
   std::vector<AnfNodePtr> inputs;
+
   auto prim = op_exec_info->py_primitive;
+  const auto &signature = prim->signatures();
+
   inputs.push_back(NewValueNode(prim));
 
   size_t size = op_exec_info->op_inputs.size();
+  auto sig_size = signature.size();
   // ignore signature for cast op
+  if (sig_size > 0 && sig_size != size) {
+    MS_EXCEPTION(ValueError) << op_exec_info->op_name << " inputs size " << size << " does not match the requires "
+                             << "inputs size " << sig_size;
+  }
   bool is_cast_op = (op_exec_info->op_name == "Cast");
   if (!is_cast_op) {
-    const auto &signature = prim->signatures();
     for (size_t i = 0; i < size; i++) {
       auto obj = op_exec_info->op_inputs[i];
       auto sig = SignatureEnumRW::kRWDefault;
-      if (signature.size() > 0) {
+      if (sig_size > 0) {
         sig = signature[i].rw;
       }
       MS_LOG(DEBUG) << "check mix precision " << op_exec_info->op_name << " input " << i << " "
diff --git a/mindspore/ccsrc/pybind_api/ir/tensor_py.cc b/mindspore/ccsrc/pybind_api/ir/tensor_py.cc
index f9636aacb9..7db7e22162 100644
--- a/mindspore/ccsrc/pybind_api/ir/tensor_py.cc
+++ b/mindspore/ccsrc/pybind_api/ir/tensor_py.cc
@@ -455,7 +455,7 @@ REGISTER_PYBIND_DEFINE(Tensor, ([](const py::module *m) {
                                   >>> data.set_dtype(mindspore.int32)
                                   mindspore.int32
                               )mydelimiter")
-                           .def("set_cast_dtype", &Tensor::set_cast_dtype)
+                           .def("set_cast_dtype", &Tensor::set_cast_dtype, py::arg("dtype") = nullptr)
                            .def("__str__", &Tensor::ToString)
                            .def("__repr__", &Tensor::ToStringRepr)
                            .def(py::pickle(
diff --git a/mindspore/common/api.py b/mindspore/common/api.py
index e099ed18d5..279a93dc8a 100644
--- a/mindspore/common/api.py
+++ b/mindspore/common/api.py
@@ -292,7 +292,6 @@ class _PynativeExecutor:
     def __init__(self):
         self._executor = PynativeExecutor_.get_instance()
 
-    #TODO(kpy):add a type arg
     def new_graph(self, obj, *args, **kwargs):
         self._executor.new_graph(obj, *args, *(kwargs.values()))
 
diff --git a/mindspore/core/ir/tensor.h b/mindspore/core/ir/tensor.h
index 8689980268..94c0329296 100644
--- a/mindspore/core/ir/tensor.h
+++ b/mindspore/core/ir/tensor.h
@@ -269,7 +269,7 @@ class Tensor : public MetaTensor {
 
   std::string id() const { return id_; }
   TypePtr cast_dtype() { return cast_dtype_; }
-  void set_cast_dtype(TypePtr dtype) { cast_dtype_ = dtype; }
+  void set_cast_dtype(TypePtr dtype = nullptr) { cast_dtype_ = dtype; }
 
   void SetNeedWait(bool need_wait) {
     if (event_ != nullptr) {
diff --git a/mindspore/nn/cell.py b/mindspore/nn/cell.py
index e509815587..ee1832ab94 100755
--- a/mindspore/nn/cell.py
+++ b/mindspore/nn/cell.py
@@ -582,10 +582,13 @@ class Cell(Cell_):
             param (Parameter): The parameter to cast.
         """
         if hasattr(self, "_mindspore_flags"):
-            if self._mindspore_flags.get('fp16'):
-                param.set_cast_dtype(mstype.float16)
             if self._mindspore_flags.get('fp32'):
                 param.set_cast_dtype(mstype.float32)
+            elif self._mindspore_flags.get('fp16'):
+                param.set_cast_dtype(mstype.float16)
+            else:
+                # retest dtype
+                param.set_cast_dtype()
         return param
 
     def insert_child_to_cell(self, child_name, child):
diff --git a/tests/ut/python/ops/test_math_ops.py b/tests/ut/python/ops/test_math_ops.py
index 0c84bd1ef5..db93c3a5ec 100755
--- a/tests/ut/python/ops/test_math_ops.py
+++ b/tests/ut/python/ops/test_math_ops.py
@@ -464,7 +464,7 @@ raise_set = [
         'block': (lambda x: P.StridedSlice(new_axis_mask="1.1"), {'exception': TypeError}),
         'desc_inputs': [0]}),
     ('AssignAdd_Error', {
-        'block': (P.AssignAdd(), {'exception': IndexError}),
+        'block': (P.AssignAdd(), {'exception': ValueError}),
         'desc_inputs': [[1]]}),
 ]