diff --git a/app/controllers/compare_controller.rb b/app/controllers/compare_controller.rb
index 63ca58aa6..4b6860153 100644
--- a/app/controllers/compare_controller.rb
+++ b/app/controllers/compare_controller.rb
@@ -6,26 +6,48 @@ class CompareController < ApplicationController
   end
 
   def show
+    load_compare_params
     compare
+    @merge_message = get_merge_message
   end
 
   private
+  def get_merge_message 
+    if @base.blank? || @head.blank?
+      return "请选择分支"
+    else
+      if @head.include?(":")
+        fork_project = @project.forked_projects.joins(:owner).where(users: {login: @head.to_s.split("/")[0]}).take
+        return "请选择正确的仓库" unless fork_project.present?
+        @exist_pullrequest = @project.pull_requests.where(is_original: true, head: @head.to_s.split(":")[1], base: @base, status: 0, fork_project_id: fork_project.id).take
+      else 
+        @exist_pullrequest = @project.pull_requests.where(is_original: false, head: @base, base: @head, status: 0).take
+      end
+      if @exist_pullrequest.present?
+        return "在这些分支之间的合并请求已存在：<a href='/projects/#{@owner.login}/#{@project.identifier}/pulls/#{@exist_pullrequest.id}/Messagecount'>#{@exist_pullrequest.try(:title)}</a>"
+      else 
+        if @compare_result["Commits"].blank? && @compare_result["Diff"].blank?
+          return "分支内容相同，无需创建合并请求"
+        end
+      end
+    end
+    return "可以合并"
+  end
+
   def compare
-    base, head = compare_params
 
     # TODO: 处理fork的项目向源项目发送PR的base、head参数问题
     @compare_result ||=
-      head.include?(":") ? gitea_compare(base, head) : gitea_compare(head, base)
+      @head.include?(":") ? gitea_compare(@base, @head) : gitea_compare(@head, @base)
   end
 
-  def compare_params
-    base = Addressable::URI.unescape(params[:base])
-    head = params[:head].include?('json') ? params[:head]&.split('.json')[0] : params[:head]
+  def load_compare_params
+    @base = Addressable::URI.unescape(params[:base])
+    @head = params[:head].include?('json') ? params[:head]&.split('.json')[0] : params[:head]
 
-    [base, head]
   end
 
   def gitea_compare(base, head)
-    Gitea::Repository::Commits::CompareService.call(@owner.login, @project.identifier, base, head)
+    Gitea::Repository::Commits::CompareService.call(@owner.login, @project.identifier, @base, @head)
   end
 end
diff --git a/app/views/compare/show.json.jbuilder b/app/views/compare/show.json.jbuilder
index 8b75fa3dd..91260e560 100644
--- a/app/views/compare/show.json.jbuilder
+++ b/app/views/compare/show.json.jbuilder
@@ -83,3 +83,4 @@ json.diff do
 
   end
 end
+json.message @merge_message
\ No newline at end of file