diff --git a/app/controllers/student_work_controller.rb b/app/controllers/student_work_controller.rb
index adfcd6263..8f3ebff98 100644
--- a/app/controllers/student_work_controller.rb
+++ b/app/controllers/student_work_controller.rb
@@ -597,6 +597,7 @@ class StudentWorkController < ApplicationController
       student_work.description = params[:student_work][:description]
       student_work.homework_common_id = @homework.id
       student_work.user_id = User.current.id
+      student_work.commit_time = Time.now
       student_work.save_attachments(params[:attachments])
       render_attachment_warning_if_needed(student_work)
       if @homework.homework_type == 3 && @homework.homework_detail_group.base_on_project == 1
@@ -791,7 +792,7 @@ class StudentWorkController < ApplicationController
         end
       end
     elsif @homework.homework_type == 1
-      @work.update_attributes(:work_status => 0, :name => "#{@homework.name}的作品提交", :description => nil, :late_penalty => 0)
+      @work.update_attributes(:work_status => 0, :name => "#{@homework.name}的作品提交", :description => nil, :late_penalty => 0, :commit_time => nil)
     end
     @student_work = StudentWork.new
     respond_to do |format|
@@ -826,7 +827,7 @@ class StudentWorkController < ApplicationController
     @new_score.user_id = User.current.id
     @new_score.student_work_id = @work.id
     if @is_teacher && @work.work_status == 0
-      @work.update_column('work_status', 1)
+      @work.update_attributes(:work_status => 1, :commit_time => Time.now)
     end
     if User.current.admin?
       @new_score.reviewer_role = 1
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 54d43c891..3b9324d6a 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -1004,6 +1004,7 @@ class UsersController < ApplicationController
         student_work.work_status = 1
       end
 
+      student_work.commit_time = Time.now
       student_work.save
       send_message_to_teacher(student_work)
       homework.update_column(:updated_at, Time.now)
diff --git a/app/models/student_work.rb b/app/models/student_work.rb
index 3ba3ee2b2..09ef15583 100644
--- a/app/models/student_work.rb
+++ b/app/models/student_work.rb
@@ -1,6 +1,6 @@
 #学生提交作品表
 class StudentWork < ActiveRecord::Base
-  attr_accessible :name, :description, :homework_common_id, :user_id, :final_score, :teacher_score, :student_score, :teaching_asistant_score, :project_id, :is_test, :simi_id, :simi_value, :work_status
+  attr_accessible :name, :description, :homework_common_id, :user_id, :final_score, :teacher_score, :student_score, :teaching_asistant_score, :project_id, :is_test, :simi_id, :simi_value, :work_status, :commit_time
 
   belongs_to :homework_common
   belongs_to :user
diff --git a/app/views/users/_course_homework.html.erb b/app/views/users/_course_homework.html.erb
index ded407f8c..1b55b08f6 100644
--- a/app/views/users/_course_homework.html.erb
+++ b/app/views/users/_course_homework.html.erb
@@ -135,9 +135,9 @@
       </div>
       <div class="cl"></div>
       <% if activity.student_works.has_committed.count != 0 %>
-        <% sw = activity.student_works.has_committed.reorder("created_at desc").first %>
+        <% sw = activity.student_works.has_committed.reorder("commit_time desc").first %>
         <div class="mt10 homepagePostDeadline mb10">
-          #&nbsp;<%=time_from_now sw.created_at %><%= link_to sw.user.show_name, user_activities_path(sw.user_id), :class => "newsBlue ml5 mr5"%>提交了作品
+          #&nbsp;<%=time_from_now sw.commit_time %><%= link_to sw.user.show_name, user_activities_path(sw.user_id), :class => "newsBlue ml5 mr5"%>提交了作品
         </div>
     <% end %>
     <div class="cl"></div>
diff --git a/app/views/users/_user_homework_detail.html.erb b/app/views/users/_user_homework_detail.html.erb
index 990a193cc..aee307963 100644
--- a/app/views/users/_user_homework_detail.html.erb
+++ b/app/views/users/_user_homework_detail.html.erb
@@ -146,9 +146,9 @@
       </div>
       <div class="cl"></div>
       <% if homework_common.student_works.has_committed.count != 0 %>
-          <% sw = homework_common.student_works.has_committed.reorder("created_at desc").first %>
+          <% sw = homework_common.student_works.has_committed.reorder("commit_time desc").first %>
           <div class="mt10 homepagePostDeadline mb10">
-            #&nbsp;<%=time_from_now sw.created_at %><%= link_to sw.user.show_name, user_activities_path(sw.user_id), :class => "newsBlue ml5 mr5"%>提交了作品
+            #&nbsp;<%=time_from_now sw.commit_time %><%= link_to sw.user.show_name, user_activities_path(sw.user_id), :class => "newsBlue ml5 mr5"%>提交了作品
           </div>
       <% end %>
       <div class="cl"></div>
diff --git a/db/migrate/20160810080942_add_commit_time_to_student_work.rb b/db/migrate/20160810080942_add_commit_time_to_student_work.rb
new file mode 100644
index 000000000..2301d7db8
--- /dev/null
+++ b/db/migrate/20160810080942_add_commit_time_to_student_work.rb
@@ -0,0 +1,16 @@
+class AddCommitTimeToStudentWork < ActiveRecord::Migration
+  def change
+    add_column :student_works, :commit_time, :datetime
+
+    count = StudentWork.all.count / 30 + 2
+    transaction do
+      for i in 1 ... count do i
+        StudentWork.page(i).per(30).each do |work|
+          if work.work_status != 0
+            work.update_column("commit_time", work.created_at)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index d8b93da88..3b812eb3d 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20160729124833) do
+ActiveRecord::Schema.define(:version => 20160810080942) do
 
   create_table "activities", :force => true do |t|
     t.integer  "act_id",                                  :null => false
@@ -1840,6 +1840,7 @@ ActiveRecord::Schema.define(:version => 20160729124833) do
     t.integer  "simi_value"
     t.float    "work_score"
     t.integer  "work_status",                                   :default => 0
+    t.datetime "commit_time"
   end
 
   add_index "student_works", ["homework_common_id", "user_id"], :name => "index_student_works_on_homework_common_id_and_user_id"