diff --git a/apps/qm/serializers.py b/apps/qm/serializers.py
index e83b1903..66f95b38 100644
--- a/apps/qm/serializers.py
+++ b/apps/qm/serializers.py
@@ -13,6 +13,16 @@ class DefectSerializer(CustomModelSerializer):
         fields = '__all__'
         read_only_fields = EXCLUDE_FIELDS
 
+    def create(self, validated_data):
+        code = validated_data["code"]
+        if Defect.objects.get_queryset(all=True).filter(code=code).exists():
+            raise ValidationError("缺陷标识已存在")
+        return super().create(validated_data)
+
+    def update(self, instance, validated_data):
+        validated_data.pop("code", None)
+        return super().update(instance, validated_data)
+
 class TestItemSerializer(CustomModelSerializer):
     class Meta:
         model = TestItem