diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 29e6a4980..ba1a51343 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -1489,8 +1489,8 @@ class UsersController < ApplicationController
       # 减少数据库交互
       watched_user_ids = User.watched_by(@user.id).count == 0 ? " " : ("," + User.watched_by(@user.id).map{|u| u.id.to_s }.join(','))
       user_ids = "(" + @user.id.to_s + watched_user_ids + ")"
-      watched_user_blog_ids = Blog.select("id").where("author_id in #{user_ids}").map { |blog| blog.id}.join(",")
-      blog_ids = "(" + watched_user_blog_ids + ")"
+      watched_user_blog_ids = Blog.select("id").where("author_id in #{user_ids}")
+      blog_ids = watched_user_blog_ids.empty? ? "(-1)" : "(" + watched_user_blog_ids.map { |blog| blog.id}.join(",") + ")"
 
       @user_activities = UserActivity.where("(container_type = 'Project' and container_id in #{user_project_ids} and act_type in #{project_types})" +
                                                 "or (container_type = 'Course' and container_id in #{user_course_ids} and act_type in #{course_types}) "+