diff --git a/go.mod b/go.mod
index fa39702..cae35ee 100644
--- a/go.mod
+++ b/go.mod
@@ -19,6 +19,7 @@ require (
 	github.com/stretchr/testify v1.7.0
 	github.com/talos-systems/talos/pkg/machinery v0.0.0-20210625144407-2060ceaa0b16
 	golang.org/x/mod v0.4.2 // indirect
+	golang.org/x/text v0.3.6
 	golang.org/x/tools v0.1.3
 	gopkg.in/yaml.v2 v2.4.0
 	honnef.co/go/tools v0.1.4 // indirect
diff --git a/parser/annotator.go b/parser/annotator.go
index 2109185..03babe1 100644
--- a/parser/annotator.go
+++ b/parser/annotator.go
@@ -2,6 +2,7 @@ package beeParser
 
 import (
 	"fmt"
+	"go/types"
 	"strconv"
 	"strings"
 )
@@ -33,7 +34,7 @@ func handleTailWhitespace(s string) string {
 	return s[0:i]
 }
 
-//handle value to remove head and tail space.
+// Handle value to remove head and tail space.
 func handleWhitespaceValues(values []string) []interface{} {
 	res := make([]interface{}, 0)
 	for _, v := range values {
@@ -44,7 +45,7 @@ func handleWhitespaceValues(values []string) []interface{} {
 	return res
 }
 
-//try to transfer string to original type
+// Transfer string to original type
 func transferType(str string) interface{} {
 	if res, err := strconv.Atoi(str); err == nil {
 		return res
@@ -55,8 +56,8 @@ func transferType(str string) interface{} {
 	return str
 }
 
-//parse annotation to generate array with key and values
-//start with "@" as a key-value pair,key and values are separated by a space,wrap to distinguish values.
+// Parse annotation to generate array with key and values
+// start with "@" as a key-value pair,key and values are separated by a space,wrap to distinguish values.
 func (a *Annotation) Annotate(annotation string) map[string]interface{} {
 	results := make(map[string]interface{})
 	//split annotation with '@'
@@ -75,20 +76,54 @@ func (a *Annotation) Annotate(annotation string) map[string]interface{} {
 	return results
 }
 
-//create new annotation
-//parse "Key","Default","Description" by annotation
-//the type of "Key" and "Description" is string, "Default" is interface{}
-func NewAnnotation(annotation string) *Annotation {
+// Create new annotation,parse "Key","Default","Description" by annotation.
+// If key and default value is empty by annotaion, set default key and value
+// by params, default value according defaultType to generate
+func NewAnnotation(annotation, defaultKey string, defaultType types.Type) *Annotation {
 	a := &Annotation{}
 	kvs := a.Annotate(annotation)
 	if v, ok := kvs["Key"]; ok {
 		a.Key = fmt.Sprintf("%v", v)
 	}
 	if v, ok := kvs["Description"]; ok {
-		a.Description = fmt.Sprintf("%v", v)
+		if ss, ok := v.([]interface{}); ok {
+			for i, s := range ss {
+				if i == 0 {
+					a.Description += s.(string)
+					continue
+				}
+				a.Description += "\n" + s.(string)
+			}
+		} else {
+			a.Description = fmt.Sprintf("%v", v)
+		}
 	}
 	if v, ok := kvs["Default"]; ok {
 		a.Default = v
 	}
+	if a.Key == "" {
+		//if key by parse is empty, set a default key
+		a.Key = defaultKey
+	}
+	if a.Default == nil {
+		//if default value is nil, set the default value according to the defaultType
+		a.Default = getDefaultValue(defaultType)
+	}
 	return a
 }
+
+// Get the default value according to the t, process bool/string/int
+func getDefaultValue(t types.Type) interface{} {
+	switch tys := t.(type) {
+	case *types.Basic:
+		switch tys.Kind() {
+		case types.Bool:
+			return false
+		case types.Int, types.Int16, types.Int8, types.Int32, types.Int64, types.Uint, types.Uint8, types.Uint16, types.Uint32, types.Uint64, types.Uintptr, types.Float32, types.Float64:
+			return 0
+		case types.String:
+			return ""
+		}
+	}
+	return nil
+}
diff --git a/parser/formatter.go b/parser/formatter.go
index 2dbdbf9..e9a847a 100644
--- a/parser/formatter.go
+++ b/parser/formatter.go
@@ -2,6 +2,8 @@ package beeParser
 
 import (
 	"encoding/json"
+	"io/ioutil"
+	"strings"
 
 	"github.com/talos-systems/talos/pkg/machinery/config/encoder"
 )
@@ -10,10 +12,7 @@ type JsonFormatter struct {
 }
 
 func (f *JsonFormatter) FieldFormatFunc(field *StructField) ([]byte, error) {
-	annotation := NewAnnotation(field.Doc + field.Comment)
-	if annotation.Key == "" {
-		annotation.Key = field.Name
-	}
+	annotation := NewAnnotation(field.Doc+field.Comment, field.Name, field.Type)
 	res := map[string]interface{}{}
 	if field.NestedType != nil {
 		res[annotation.Key] = field.NestedType
@@ -41,24 +40,34 @@ type Result map[string]interface{}
 func (c Result) Doc() *encoder.Doc {
 	return &result
 }
+
 func (f *YamlFormatter) FieldFormatFunc(field *StructField) ([]byte, error) {
-	annotation := NewAnnotation(field.Doc + field.Comment)
-	if annotation.Key == "" {
-		annotation.Key = field.Name
-	}
+	annotation := NewAnnotation(field.Doc+field.Comment, field.Name, field.Type)
 	res := Result{}
 	// add head comment for this field
 	res.Doc().Comments[encoder.HeadComment] = annotation.Description
 	if field.NestedType != nil {
-		b, _ := field.NestedType.FormatFunc(field.NestedType)
+		// nestedType format result as this field value
+		b, err := field.NestedType.FormatFunc(field.NestedType)
+		if err != nil {
+			return nil, err
+		}
 		res[annotation.Key] = string(b)
 	} else {
 		res[annotation.Key] = annotation.Default
 	}
+
 	encoder := encoder.NewEncoder(&res, []encoder.Option{
 		encoder.WithComments(encoder.CommentsAll),
 	}...)
-	return encoder.Encode()
+	encodeByte, err := encoder.Encode()
+	if err != nil {
+		return nil, err
+	}
+	// when field.NestedType != nil, the key and nested value strings are encoded with "|"
+	// remove "|" by string replace
+	encodeByte = []byte(strings.Replace(string(encodeByte), annotation.Key+": |", annotation.Key+":", 1))
+	return encodeByte, nil
 }
 
 func (f *YamlFormatter) StructFormatFunc(node *StructNode) ([]byte, error) {
@@ -71,5 +80,10 @@ func (f *YamlFormatter) StructFormatFunc(node *StructNode) ([]byte, error) {
 }
 
 func (f *YamlFormatter) Marshal(node *StructNode) ([]byte, error) {
-	return node.FormatFunc(node)
+	res, err := node.FormatFunc(node)
+	if err != nil {
+		return nil, err
+	}
+	ioutil.WriteFile(node.Name+".yaml", res, 0667)
+	return res, nil
 }
diff --git a/parser/formatter_test.go b/parser/formatter_test.go
index 1cd6f67..5842381 100644
--- a/parser/formatter_test.go
+++ b/parser/formatter_test.go
@@ -25,6 +25,7 @@ type StructA struct {
 		// @Default https://github.com/beego/bee
 		// 			https://github.com/beego
 		// @Description comment of a of field2
+		//  ssssss
 		a string
 		// @Key b
 		// @Default https://github.com/beego/bee https://github.com/beego
@@ -38,6 +39,11 @@ type StructA struct {
 	// @Key NestField
 	// @Description comment of NestField
 	NestField StructB
+	Field5 float32
+	Field6 bool
+	Field7 string
+	Field8 interface{}
+	Field9 *StructB
 }
 `
 
@@ -105,16 +111,22 @@ func ExampleYamlFormatter() {
 	// # comment of field1
 	// Field1: test
 	// # comment of b of field2
-	// Field2: |
+	// Field2:
 	//     # comment of a of field2
+	//     # ssssss
 	//     a:
 	//         - https://github.com/beego/bee
 	//         - https://github.com/beego
 	//     # comment of b of field2
 	//     b: https://github.com/beego/bee https://github.com/beego
 	// # comment of field3
-	// Field3: null
+	// Field3: 0
 	// Field4: false
-	// NestField: |
+	// NestField:
 	//     FieldB1: null
+	// Field5: 0
+	// Field6: false
+	// Field7: ""
+	// Field8: null
+	// Field9: null
 }