diff --git a/app/controllers/homework_common_controller.rb b/app/controllers/homework_common_controller.rb
index c35555780..0f267f212 100644
--- a/app/controllers/homework_common_controller.rb
+++ b/app/controllers/homework_common_controller.rb
@@ -9,10 +9,10 @@ class HomeworkCommonController < ApplicationController
   before_filter :find_course, :only => [:index,:new,:create]
   before_filter :find_homework, :only => [:edit,:update,:alert_anonymous_comment,:start_anonymous_comment,:stop_anonymous_comment,:destroy,:start_evaluation_set,
                                           :set_evaluation_attr,:score_rule_set,:alert_forbidden_anonymous_comment,:alert_open_student_works,:open_student_works,
-                                          :set_score_open,:alert_score_open_modal,:add_to_homework_bank,:publish_homework,:setting,:set_public,:homework_setting]
+                                          :set_score_open,:alert_score_open_modal,:add_to_homework_bank,:publish_homework,:setting,:set_public,:homework_setting,:update_explanation]
   before_filter :teacher_of_course, :only => [:new, :create, :edit, :update, :destroy, :start_anonymous_comment, :stop_anonymous_comment, :alert_anonymous_comment,
                                               :start_evaluation_set,:set_evaluation_attr,:score_rule_set,:alert_forbidden_anonymous_comment,:alert_open_student_works,
-                                              :open_student_works,:add_to_homework_bank,:publish_homework]
+                                              :open_student_works,:add_to_homework_bank,:publish_homework,:update_explanation]
   before_filter :member_of_course, :only => [:index,:setting]
 
   def index
@@ -471,6 +471,13 @@ class HomeworkCommonController < ApplicationController
     end
   end
 
+  #更新作业说明
+  def update_explanation
+    @is_teacher = User.current.admin? || User.current.allowed_to?(:as_teacher, @course)
+    @homework.update_attribute('explanation', params[:homework_common][:explanation])
+    redirect_to student_work_index_path(:homework => @homework.id, :tab => 2)
+  end
+
   #加入到题库
   def add_to_homework_bank
     if params[:type] && (params[:type].to_i == 1 || params[:type].to_i == 3)
diff --git a/app/views/student_work/_homework_explanation.html.erb b/app/views/student_work/_homework_explanation.html.erb
new file mode 100644
index 000000000..059c7b3ac
--- /dev/null
+++ b/app/views/student_work/_homework_explanation.html.erb
@@ -0,0 +1,28 @@
+<%= javascript_include_tag("/assets/kindeditor/kindeditor",'/assets/kindeditor/pasteimg') %>
+
+<p class="clearfix">
+  <span class="fl font-14 font-bd mt5">作业说明:</span>
+  <a href="javascript:void(0)" class="fr white-btn orange-btn edit-btn"><i class="fa fa-pencil mr5"></i>编辑</a>
+  <a href="javascript:void(0)" class="fr white-btn orange-btn save-btn undis"><i class="fa fa-floppy-o mr5"></i>保存</a>
+  <a href="javascript:void(0)" class="fr white-btn orange-btn cancel-btn undis mr10"><i class="fa fa-undo mr5"></i>取消</a>
+  <span id="homework_explanation_notice" class="fr color-red mr10 undis">请输入作业说明</span>
+</p>
+<div class="upload_img list_style break_word justify" id="homework_explanation_show" style="text-indent: 25px;">
+  <%= @homework.explanation.blank? ? "无" : @homework.explanation.html_safe %>
+</div>
+<div id="homework_explanation_edit" class="undis">
+  <%= labelled_form_for @homework, :url =>{:controller=>'homework_common',:action => 'update_explanation', :id => @homework.id}, :html => {:id => 'homework_explanation_form'}, :method => "post" do |f| %>
+      <%= f.kindeditor :explanation, :editor_id => 'homework_explanation_editor',
+                       :owner_id => @homework.nil? ? 0: @homework.id,
+                       :owner_type => OwnerTypeHelper::HOMEWORKCOMMON,
+                       :placeholder => "请在此输入您的作业说明",
+                       :width => '100%',
+                       :height => 200,
+                       :minHeight=> 200,
+                       :class => 'talk_text fl',
+                       :input_html => { :id => 'homework_content',
+                                        :class => 'talk_text fl',
+                                        :maxlength => 5000 }
+      %>
+  <% end %>
+</div>
diff --git a/app/views/student_work/_student_work_replies.html.erb b/app/views/student_work/_student_work_replies.html.erb
index 814d4df18..97d80284a 100644
--- a/app/views/student_work/_student_work_replies.html.erb
+++ b/app/views/student_work/_student_work_replies.html.erb
@@ -1,3 +1,6 @@
+<% content_for :header_tags do %>
+    <%= import_ke(enable_at: true, prettify: false, init_activity: true) %>
+<% end %>
 <% count = @homework.journals_for_messages.count %>
 <% comments = @homework.journals_for_messages.reorder("created_on desc") %>
 <% no_children_comments = get_no_children_comments_all comments %>
@@ -23,4 +26,10 @@
     <div class="cl"></div>
   </div>
 </div>
-<!--comment_item_cont end-->
\ No newline at end of file
+<!--comment_item_cont end-->
+
+<script>
+    $(function(){
+        sd_create_editor_from_data(<%= @homework.id %>, null, "100%", "<%= @homework.class.to_s %>");
+    });
+</script>
\ No newline at end of file
diff --git a/app/views/student_work/index.html.erb b/app/views/student_work/index.html.erb
index 0d15ffd2d..20a83ec0c 100644
--- a/app/views/student_work/index.html.erb
+++ b/app/views/student_work/index.html.erb
@@ -5,7 +5,6 @@
     <%= stylesheet_link_tag '/editormd/css/editormd','/editormd/css/editormd.min.css' %>
 <%= javascript_include_tag '/editormd/lib/marked.min.js','/editormd/lib/prettify.min.js','/editormd/lib/raphael.min.js','/editormd/lib/underscore.min.js','/editormd/lib/sequence-diagram.min.js',
                            '/editormd/lib/flowchart.min.js','/editormd/lib/jquery.flowchart.min.js','/editormd/editormd.js'%>
-<%= import_ke(enable_at: true, prettify: false, init_activity: true) %>
 <% end %>
 <style>
     .editormd-html-preview {
@@ -15,9 +14,6 @@
 <% is_group_project_homework = @homework.homework_type == 3 && @homework.homework_detail_group.base_on_project == 1 %>
 
 <script type="text/javascript">
-    $(function(){
-        sd_create_editor_from_data(<%= @homework.id %>, null, "100%", "<%= @homework.class.to_s %>");
-    });
     function HoverLi(n){
         for(var i=1;i<=4;i++){
             $('#edu-tab-nav-'+i).removeClass('background-orange');
@@ -68,46 +64,6 @@
             <%= link_to '查看实训', shixun_path(@homework.homework_commons_shixuns.shixun), :target => "_blank", :class => 'fr mt5 mr5 white-btn orange-btn' %>
         <% end %>
         <%= link_to "导出成绩", student_work_index_path(:homework => @homework.id,:order => @order, :sort => @b_sort, :name => @name, :group => @group, :comment => @comment, :status => @status, :format => 'xls'),:class=>'fl mt5 mr10 white-btn orange-btn', :id => "export_student_work"%>
-
-        <!--<a href="javascript:void(0);" class="font-16"><i class="fa fa-bars mr10"></i></a>-->
-        <!--<ul class="edu-position-hide undis" style="left:-85px;">
-          <%# if @homework.homework_type != 4 %>
-              <li>
-                <%#= link_to l(:button_edit), edit_homework_common_path(@homework) %>
-              </li>
-          <%# end %>
-          &lt;!&ndash;<li>&ndash;&gt;
-            &lt;!&ndash;<%#= link_to "设置", setting_homework_common_path(@homework) %>&ndash;&gt;
-          &lt;!&ndash;</li>&ndash;&gt;
-          <%# if @homework.homework_type == 4 %>
-              <li>
-                <%#= link_to '进入实训', shixun_path(@homework.homework_commons_shixuns.shixun), :target => "_blank" %>
-              </li>
-          <%# end %>
-          <%# unless @homework.is_public %>
-              <li id="set_homework_public_<%#= @homework.id %>">
-                <a href="javascript:void(0);" onclick="s_op_confirm_box('<%#= set_public_homework_common_path(@homework) %>', '您确定要公开吗？<br/>公开后不能重设为私有')">设为公开</a>
-              </li>
-          <%# end %>
-          <%# if (User.current.teacher_of_course(@homework.course) || @homework.user == User.current) && User.current.homework_banks.where(:homework_common_id => @homework.id).empty? %>
-              <li class="add_to_homework_bank_<%#= @homework.id %>">
-                <%#= link_to "加入题库", add_to_homework_bank_homework_common_path(@homework, :type => 1), :remote => true %>
-              </li>
-          <%# end %>
-          <%# if @homework.user == User.current %>
-              <%# if @homework.is_update && !User.current.homework_banks.where(:homework_common_id => @homework.id).blank? %>
-                  <li class="add_to_homework_bank_<%#= @homework.id %>">
-                    <%#= link_to "同步到题库", add_to_homework_bank_homework_common_path(@homework, :type => 2), :remote => true %>
-                  </li>
-                  <li class="add_to_homework_bank_<%#= @homework.id %>">
-                    <%#= link_to "另存到题库", add_to_homework_bank_homework_common_path(@homework, :type => 3), :remote => true %>
-                  </li>
-              <%# end %>
-          <%# end %>
-          <li>
-            <a href="javascript:void(0)" onclick="delete_confirm_box_3('<%#= homework_common_path(@homework) %>', '您确定要删除吗？<br/>已提交作品将全部被删除，不可恢复')">删除</a>
-          </li>
-        </ul>-->
       </div>
   <% else %>
       <%= user_work_status @homework %>
@@ -132,16 +88,19 @@
       <% end %>
     </div>
 
-    <% if false%>
-    <div class="homework_explain" style="padding:<%= @is_teacher ? '5px' : '15px' %> 15px;">
-        <p class="clearfix">
-          <span class="fl font-14 font-bd mt5">作业说明:</span>
-          <a href="javascript:void(0)" class="fr white-btn orange-btn edit-btn"><i class="fa fa-pencil mr5"></i>编辑</a>
-          <a href="javascript:void(0)" class="fr white-btn orange-btn save-btn undis"><i class="fa fa-floppy-o mr5"></i>保存</a>
-        </p>
-        <p class="break-word" style="text-indent: 25px;">兴趣的信息，利用所学到的有关“协议与编码器”/解码器/转换器/处理器”的思维，为该类信息设计协议</p>
-        <p></p><!--放置ke编辑器点击，点击编辑显示-->
-    </div>
+    <% if @homework.homework_type == 4 && (!@homework.explanation.blank? || @is_teacher) %>
+        <div class="homework_explain" id="homework_explanation_div" style="padding:<%= @is_teacher ? '5px' : '15px' %> 15px;">
+          <% if @is_teacher %>
+              <%= render :partial => "student_work/homework_explanation" %>
+          <% elsif !@homework.explanation.blank? %>
+              <p>
+                <span class="fl font-14 font-bd mt5">作业说明:</span>
+              </p>
+              <div class="upload_img list_style break_word justify" style="text-indent: 25px;">
+                <%= @homework.explanation.html_safe %>
+              </div>
+          <% end %>
+        </div>
     <% end %>
 
     <ul class="panel-mes-head" style="padding:<%= @is_teacher ? '5px' : '15px' %> 15px;">
@@ -421,11 +380,27 @@
       //编辑、保存作业说明
       $(".edit-btn").live("click",function(){
           $(this).siblings(".save-btn").show();
+          $(this).siblings(".cancel-btn").show();
           $(this).hide();
+          $("#homework_explanation_show").hide();
+          $("#homework_explanation_edit").show();
+      });
+      $(".cancel-btn").live("click",function(){
+          $(this).siblings(".edit-btn").show();
+          $(this).siblings(".save-btn").hide();
+          $(this).hide();
+          $("#homework_explanation_show").show();
+          $("#homework_explanation_edit").hide();
+          $("#homework_explanation_notice").hide();
       });
       $(".save-btn").live("click",function(){
-          $(this).siblings(".edit-btn").show();
-          $(this).hide();
-      })
+          if(homework_explanation_editor.isEmpty()){
+              $("#homework_explanation_notice").show();
+          } else{
+              $("#homework_explanation_notice").hide();
+              homework_explanation_editor.sync();
+              $("#homework_explanation_form").submit();
+          }
+      });
   })
 </script>
\ No newline at end of file
diff --git a/config/routes.rb b/config/routes.rb
index f879b4ac6..9e86b1be4 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -590,6 +590,7 @@ RedmineApp::Application.routes.draw do
       get 'setting'
       post 'homework_setting'
       get 'set_public'
+      post 'update_explanation'
     end
 
     collection do
diff --git a/db/migrate/20171013115401_add_explanation_to_homework_common.rb b/db/migrate/20171013115401_add_explanation_to_homework_common.rb
new file mode 100644
index 000000000..edf21250c
--- /dev/null
+++ b/db/migrate/20171013115401_add_explanation_to_homework_common.rb
@@ -0,0 +1,5 @@
+class AddExplanationToHomeworkCommon < ActiveRecord::Migration
+  def change
+    add_column :homework_commons, :explanation, :text
+  end
+end