diff --git a/app/controllers/discuss_demos_controller.rb b/app/controllers/discuss_demos_controller.rb
index a0955efe2..b0c9791cb 100644
--- a/app/controllers/discuss_demos_controller.rb
+++ b/app/controllers/discuss_demos_controller.rb
@@ -26,10 +26,12 @@ class DiscussDemosController < ApplicationController
 
   def destroy
     asset = Kindeditor::Asset.find_by_owner_id(params[:id])
-    filepath = File.join(Rails.root,"public","files","uploads",
-                         asset[:created_at].to_s.gsub("+0800","").to_datetime.strftime("%Y%m").to_s,
-                         asset[:asset].to_s)
-    File.delete(filepath) if File.exist?filepath
+    if !asset.nil?
+      filepath = File.join(Rails.root,"public","files","uploads",
+                           asset[:created_at].to_s.gsub("+0800","").to_datetime.strftime("%Y%m").to_s,
+                           asset[:asset].to_s)
+      File.delete(filepath) if File.exist?filepath
+    end
     DiscussDemo.destroy(params[:id])
     redirect_to :controller=> 'discuss_demos',:action => 'index'
   end