diff --git a/validator.go b/validator.go
index d6363a5..60bdc47 100644
--- a/validator.go
+++ b/validator.go
@@ -12,6 +12,9 @@ package consts
 type ValidatorRule string // 验证规则
 
 func (vr *ValidatorRule) String() string {
+	if nil == vr {
+		return ""
+	}
 	return string(*vr)
 }