diff --git a/app/helpers/users_helper.rb b/app/helpers/users_helper.rb
index b1020d938..4923c629e 100644
--- a/app/helpers/users_helper.rb
+++ b/app/helpers/users_helper.rb
@@ -582,7 +582,7 @@ module UsersHelper
     option << "请选择发布作业的课程"
     option << -1
     type << option
-    user.courses.select{|c| user.allowed_to?(:as_teacher,c)}.each do |course|
+    user.courses.visible.select("courses.*,(SELECT MAX(created_at)  FROM `course_activities` WHERE course_activities.course_id = courses.id) AS a").order("a desc").select{|c| user.allowed_to?(:as_teacher,c)}.each do |course|
       option = []
       option << course.name+"（"+course.time.to_s+course.term+"）"
       option << course.id