diff --git a/common.go b/common.go
index 828d5f7..46e5ec2 100755
--- a/common.go
+++ b/common.go
@@ -17,6 +17,7 @@ type Framer struct {
 // ToFixHeaderUint8 ToFixHeaderUint8
 func ToFixHeaderUint8(f Frame) uint8 {
 	typeAndFlags := encodeBool(f.GetDUP())<<3 | encodeBool(f.GetsyncOnce())<<2 | encodeBool(f.GetRedDot())<<1 | encodeBool(f.GetNoPersist())
+
 	return byte(int(f.GetFrameType()<<4) | typeAndFlags)
 }
 
@@ -28,6 +29,7 @@ func FramerFromUint8(v uint8) Framer {
 	p.SyncOnce = (v >> 2 & 0x01) > 0
 	p.DUP = (v >> 3 & 0x01) > 0
 	p.FrameType = FrameType(v >> 4)
+
 	return p
 }
 
diff --git a/connack.go b/connack.go
index ef6abe7..cae56a9 100755
--- a/connack.go
+++ b/connack.go
@@ -9,10 +9,11 @@ import (
 // ConnackPacket 连接回执包
 type ConnackPacket struct {
 	Framer
-	ServerKey  string     // 服务端的DH公钥
-	Salt       string     // salt
-	TimeDiff   int64      // 客户端时间与服务器的差值，单位毫秒。
-	ReasonCode ReasonCode // 原因码
+	ServerVersion uint8      // 服务端版本
+	ServerKey     string     // 服务端的DH公钥
+	Salt          string     // salt
+	TimeDiff      int64      // 客户端时间与服务器的差值，单位毫秒。
+	ReasonCode    ReasonCode // 原因码
 }
 
 // GetFrameType 获取包类型
@@ -24,8 +25,11 @@ func (c ConnackPacket) String() string {
 }
 
 func encodeConnack(connack *ConnackPacket, enc *Encoder, version uint8) error {
+	if version > 3 {
+		enc.WriteUint8(connack.ServerVersion)
+	}
 	enc.WriteInt64(connack.TimeDiff)
-	enc.WriteByte(connack.ReasonCode.Byte())
+	_ = enc.WriteByte(connack.ReasonCode.Byte())
 	enc.WriteString(connack.ServerKey)
 	enc.WriteString(connack.Salt)
 	return nil
@@ -33,6 +37,9 @@ func encodeConnack(connack *ConnackPacket, enc *Encoder, version uint8) error {
 
 func encodeConnackSize(packet *ConnackPacket, version uint8) int {
 	size := 0
+	if version > 3 {
+		size += VersionByteSize
+	}
 	size += TimeDiffByteSize
 	size += ReasonCodeByteSize
 	size += (len(packet.ServerKey) + StringFixLenByteSize)
@@ -47,6 +54,12 @@ func decodeConnack(frame Frame, data []byte, version uint8) (Frame, error) {
 
 	var err error
 
+	if version > 3 {
+		if connackPacket.ServerVersion, err = dec.Uint8(); err != nil {
+			return nil, errors.Wrap(err, "解码version失败！")
+		}
+	}
+
 	if connackPacket.TimeDiff, err = dec.Int64(); err != nil {
 		return nil, errors.Wrap(err, "解码TimeDiff失败！")
 	}
diff --git a/connack_test.go b/connack_test.go
index 4f2c8dd..75d2f02 100755
--- a/connack_test.go
+++ b/connack_test.go
@@ -8,10 +8,11 @@ import (
 
 func TestConnackEncodeAndDecode(t *testing.T) {
 	packet := &ConnackPacket{
-		TimeDiff:   12345,
-		ReasonCode: ReasonSuccess,
-		ServerKey:  "ServerKey",
-		Salt:       "Salt",
+		TimeDiff:      12345,
+		ReasonCode:    ReasonSuccess,
+		ServerKey:     "ServerKey",
+		Salt:          "Salt",
+		ServerVersion: 100,
 	}
 	codec := New()
 	// 编码
@@ -28,4 +29,5 @@ func TestConnackEncodeAndDecode(t *testing.T) {
 	assert.Equal(t, packet.ReasonCode, resultConnackPacket.ReasonCode)
 	assert.Equal(t, packet.ServerKey, resultConnackPacket.ServerKey)
 	assert.Equal(t, packet.Salt, resultConnackPacket.Salt)
+	assert.Equal(t, packet.ServerVersion, resultConnackPacket.ServerVersion)
 }
diff --git a/connect.go b/connect.go
index 43fb4e4..7709deb 100755
--- a/connect.go
+++ b/connect.go
@@ -18,12 +18,6 @@ type ConnectPacket struct {
 	Token           string     // token
 }
 
-// ToFixHeaderUint8 ToFixHeaderUint8
-func (c ConnectPacket) ToFixHeaderUint8() uint8 {
-	typeAndFlags := encodeBool(c.GetDUP())<<3 | encodeBool(c.GetsyncOnce())<<2 | encodeBool(c.GetRedDot())<<1 | encodeBool(c.GetNoPersist())
-	return byte(int(c.GetFrameType()<<4) | typeAndFlags)
-}
-
 // GetFrameType 包类型
 func (c ConnectPacket) GetFrameType() FrameType {
 	return CONNECT
diff --git a/protocol.go b/protocol.go
index 1ab19bd..b34ce1c 100755
--- a/protocol.go
+++ b/protocol.go
@@ -27,7 +27,7 @@ type WKProto struct {
 }
 
 // LatestVersion 最新版本
-const LatestVersion = 3
+const LatestVersion = 4
 
 // MaxRemaingLength 最大剩余长度 // 1<<28 - 1
 const MaxRemaingLength uint32 = 1024 * 1024