diff --git a/app/services/pull_requests/create_service.rb b/app/services/pull_requests/create_service.rb
index 2b4767f31..070b564d9 100644
--- a/app/services/pull_requests/create_service.rb
+++ b/app/services/pull_requests/create_service.rb
@@ -180,7 +180,7 @@ class PullRequests::CreateService < ApplicationService
   end
 
   def compare_head_base!
-    head = pull_request.is_original && @params[:merge_user_login] ? "#{@params[:merge_user_login]}/#{@project.identifier}:#{@params[:head]}" : @params[:head]
+    head = pull_request.is_original && @params[:merge_user_login] ? "#{@params[:merge_user_login]}/#{@params[:merge_project_identifier]}:#{@params[:head]}" : @params[:head]
     compare_result = Gitea::Repository::Commits::CompareService.call(@owner.login, @project.identifier, Addressable::URI.escape(@params[:base]), Addressable::URI.escape(head), @current_user.gitea_token)
     raise '分支内容相同，无需创建合并请求' if compare_result["Commits"].blank? && compare_result["Diff"].blank?
   end