diff --git a/app/Models/WorkOrder/Reply.php b/app/Models/WorkOrder/Reply.php
index 7da6cb6..bef9f8c 100644
--- a/app/Models/WorkOrder/Reply.php
+++ b/app/Models/WorkOrder/Reply.php
@@ -76,6 +76,10 @@ protected static function boot()
             // load work order
             $model->load(['workOrder']);
 
+            // throw if work order is null
+            if (is_null($model->workOrder)) {
+                throw new CommonException('Work order not found');
+            }
             throw_if($model->workOrder->status == 'pending' || $model->workOrder->status == 'error', CommonException::class, '工单状态不正确');
 
             // change work order status