diff --git a/db/migrate/20160421011543_alter_homework_end_time.rb b/db/migrate/20160421011543_alter_homework_end_time.rb
new file mode 100644
index 000000000..4470bd63b
--- /dev/null
+++ b/db/migrate/20160421011543_alter_homework_end_time.rb
@@ -0,0 +1,21 @@
+class AlterHomeworkEndTime < ActiveRecord::Migration
+  def up
+    homeworks = HomeworkCommon.where("id in (3229, 3234, 3235, 3236)");
+    unless homeworks.empty? || homeworks.nil?
+      homeworks.each do |hw|
+        hw.end_time = hw.end_time + 4
+        hm = hw.homework_detail_manual
+        hm.comment_status = 1
+        hw.student_works.each do |stu|
+          stu.late_penalty = 0
+          stu.save
+        end
+        hm.save
+        hw.save
+      end
+    end
+  end
+
+  def down
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 124870b49..7e84996e6 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 => 20160418074429) do
+ActiveRecord::Schema.define(:version => 20160421011543) do
 
   create_table "activities", :force => true do |t|
     t.integer  "act_id",                                  :null => false