diff --git a/app/models/attachment.rb b/app/models/attachment.rb
index ae23428f1..b6253de7a 100644
--- a/app/models/attachment.rb
+++ b/app/models/attachment.rb
@@ -349,11 +349,16 @@ class Attachment < ActiveRecord::Base
 
   # Deletes the file from the file system if it's not referenced by other attachments
   def delete_from_disk
-    if Attachment.where("disk_filename = ? AND id <> ?", disk_filename, id).empty?
+    #资源存在，且历史记录为0 且 该资源没有存在任何拷贝才能删除资源
+    if Attachment.where("disk_filename = ? AND id <> ?", disk_filename, id).empty?  && self.attachment_histories.count == 0 && Attachment.where('copy_from = ?',self.id) .count == 0
       delete_from_disk!
     end
   end
 
+  def destroyable
+    Attachment.where("disk_filename = ? AND id <> ?", disk_filename, id).empty?  && self.attachment_histories.count == 0 && Attachment.where('copy_from = ?',self.id) .count == 0
+  end
+
   # Returns file's location on disk
   def diskfile
     File.join(self.class.storage_path, disk_directory.to_s, disk_filename.to_s)
diff --git a/app/views/files/_course_list.html.erb b/app/views/files/_course_list.html.erb
index 653877260..e2d321b51 100644
--- a/app/views/files/_course_list.html.erb
+++ b/app/views/files/_course_list.html.erb
@@ -52,7 +52,7 @@
                                               <%end%>
                                                   <li>
                                                     <%= link_to( '删除资源', attachment_path(file),
-                                                                 :data => {:confirm => l(:text_are_you_sure)}, :method => :delete,:class => "postOptionLink") if (delete_allowed || User.current.id == file.author_id) && file.container_id == @course.id && file.container_type == "Course"%>
+                                                                 :data => {:confirm => l(:text_are_you_sure)}, :method => :delete,:class => "postOptionLink") if (delete_allowed || User.current.id == file.author_id) && file.container_id == @course.id && file.container_type == "Course" && file.destroyable %>
                                                   </li>
 
                                           <% end %>