diff --git a/structutil/field.go b/structutil/field.go
index 3419172..6be4f70 100644
--- a/structutil/field.go
+++ b/structutil/field.go
@@ -1,10 +1,12 @@
 package structutil
 
 import (
-	"github.com/duke-git/lancet/v2/pointer"
 	"reflect"
+
+	"github.com/duke-git/lancet/v2/pointer"
 )
 
+// Field is abstract struct field for provide several high level functions
 type Field struct {
 	Struct
 	field reflect.StructField
@@ -59,11 +61,13 @@ func (f *Field) Kind() reflect.Kind {
 	return f.rvalue.Kind()
 }
 
+// IsSlice check if a struct field type is slice or not
 func (f *Field) IsSlice() bool {
 	k := f.rvalue.Kind()
 	return k == reflect.Slice
 }
 
+// MapValue conver field value to map.
 func (f *Field) MapValue(value any) any {
 	val := pointer.ExtractPointer(value)
 	v := reflect.ValueOf(val)
diff --git a/structutil/struct.go b/structutil/struct.go
index 1b1d28d..914491f 100644
--- a/structutil/struct.go
+++ b/structutil/struct.go
@@ -57,7 +57,7 @@ func New(value any, tagName ...string) *Struct {
 //	 	// custom map key
 //	 	Name string `json:"myName"`
 //
-// Only the exported fields of a struct can be converted.
+// ToMap conver the exported fields of a struct to map.
 func (s *Struct) ToMap() (map[string]any, error) {
 	if !s.IsStruct() {
 		return nil, errInvalidStruct(s)
diff --git a/structutil/struct_test.go b/structutil/struct_test.go
index f5da905..eb64b61 100644
--- a/structutil/struct_test.go
+++ b/structutil/struct_test.go
@@ -1,9 +1,10 @@
 package structutil
 
 import (
-	"github.com/duke-git/lancet/v2/internal"
 	"reflect"
 	"testing"
+
+	"github.com/duke-git/lancet/v2/internal"
 )
 
 func TestStruct_ToMap(t *testing.T) {
@@ -113,6 +114,7 @@ func TestStruct_Field(t *testing.T) {
 	assert.Equal("1", a.Value())
 	assert.Equal("a", a.tag.Name)
 	assert.Equal(false, a.tag.HasOption("omitempty"))
+	assert.Equal(false, a.tag.IsEmpty())
 }
 
 func TestStruct_IsStruct(t *testing.T) {
diff --git a/structutil/tag.go b/structutil/tag.go
index 452147b..cd9f34c 100644
--- a/structutil/tag.go
+++ b/structutil/tag.go
@@ -1,10 +1,12 @@
 package structutil
 
 import (
-	"github.com/duke-git/lancet/v2/validator"
 	"strings"
+
+	"github.com/duke-git/lancet/v2/validator"
 )
 
+// Tag is abstract struct field tag
 type Tag struct {
 	Name    string
 	Options []string
@@ -18,6 +20,7 @@ func newTag(tag string) *Tag {
 	}
 }
 
+// HasOption check if a struct field tag has option setting.
 func (t *Tag) HasOption(opt string) bool {
 	for _, o := range t.Options {
 		if o == opt {
@@ -27,6 +30,7 @@ func (t *Tag) HasOption(opt string) bool {
 	return false
 }
 
+// IsEmpty check if a struct field has tag setting.
 func (t *Tag) IsEmpty() bool {
 	return validator.IsEmptyString(t.Name)
 }