diff --git a/builder.go b/builder.go
index ad64070..a820fbb 100644
--- a/builder.go
+++ b/builder.go
@@ -1,12 +1,13 @@
 package dynamicstruct
 
 import (
-	"fmt"
 	"git.zhangdeman.cn/zhangdeman/wrapper"
 	"reflect"
 	"strings"
 )
 
+const tagTpl = `json:"{TAG_NAME}" xml:"{TAG_NAME}" toml:"{TAG_NAME}" yaml:"{TAG_NAME}" ini:"{TAG_NAME}"`
+
 type nestedStruct struct {
 	Field   string
 	Builder IBuilder
@@ -69,7 +70,7 @@ func (b *builderImpl) AddField(name string, pkg string, typ any, tag string, ano
 		if len(tag) == 0 {
 			arr := strings.Split(strings.TrimSuffix(name, ".[]"), ".")
 			// 没指定tag, 字段名称作为tag名称
-			tag = strings.ReplaceAll(`json:"{TAG_NAME}" xml:"{TAG_NAME}" toml:"{TAG_NAME}" yaml:"{TAG_NAME}" ini:"{TAG_NAME}"`, "{TAG_NAME}", arr[len(arr)-1])
+			tag = strings.ReplaceAll(tagTpl, "{TAG_NAME}", arr[len(arr)-1])
 			// tag = fmt.Sprintf(`json:"%s"`, name)
 		}
 	}
@@ -121,7 +122,8 @@ func (b *builderImpl) addNestedField(nameArr []string, pkg string, typ any, tag
 		parentName := strings.Join(nameArr[:i], ".")
 		parentJsonTag := nameArr[i-1]
 		parentFieldName := wrapper.String(parentJsonTag).SnakeCaseToCamel()
-		fieldTag := fmt.Sprintf(`json:"%s"`, parentJsonTag)
+		// fieldTag := fmt.Sprintf(`json:"%s"`, parentJsonTag)
+		fieldTag := strings.ReplaceAll(tagTpl, "{TAG_NAME}", parentJsonTag)
 		if tagCfg, exist := b.structTagTable[parentName]; exist && len(tagCfg) > 0 {
 			fieldTag = tagCfg
 		}