diff --git a/app/models/course.rb b/app/models/course.rb
index 46599dbfc..a583990c1 100644
--- a/app/models/course.rb
+++ b/app/models/course.rb
@@ -50,6 +50,8 @@ class Course < ActiveRecord::Base
   validates_format_of  :name,:with =>/^[^ ]+[a-zA-Z0-9_\u4e00-\u9fa5\s\S]+$/
   validates_length_of :description, :maximum => 10000
   before_save :self_validate
+  # 公开课程变成私有课程，所有资源都变成私有
+  after_update :update_files_public
   after_create :create_board_sync, :act_as_course_activity, :act_as_course_message
   before_destroy :delete_all_members
 
@@ -213,6 +215,14 @@ class Course < ActiveRecord::Base
 
   end
 
+  def update_files_public
+    unless self.is_public?
+      self.attachments.each do |a|
+        a.update_attributes(:is_public => false)
+      end
+    end
+  end
+
   # 创建课程讨论区
   def create_board_sync
     @board = self.boards.build