diff --git a/catch/monitor/controller/Crontab.php b/catch/monitor/controller/Crontab.php
index 36daa132ac7d5b0c1d826719cf8e707e201226c6..7ad1b5d90476508acc123235802da380cb128d3e 100644
--- a/catch/monitor/controller/Crontab.php
+++ b/catch/monitor/controller/Crontab.php
@@ -73,7 +73,10 @@ public function read($id)
      */
     public function update(Request $request, $id)
     {
-        new CronExpression($request->post('cron'));
+        $post = $request->post();
+        if(isset($post['cron'])){
+            new CronExpression($request->post('cron'));
+        }
 
         return CatchResponse::success($this->model->updateBy($id, $request->post()));
     }