diff --git a/transport/internet/kcp/connection.go b/transport/internet/kcp/connection.go
index 6f2f7796..092f9b0e 100644
--- a/transport/internet/kcp/connection.go
+++ b/transport/internet/kcp/connection.go
@@ -420,16 +420,16 @@ func (this *Connection) Input(data []byte) int {
 
 		switch seg := seg.(type) {
 		case *DataSegment:
-			this.HandleOption(seg.Opt)
+			this.HandleOption(seg.Option)
 			this.receivingWorker.ProcessSegment(seg)
 			this.dataInputCond.Signal()
 		case *AckSegment:
-			this.HandleOption(seg.Opt)
+			this.HandleOption(seg.Option)
 			this.sendingWorker.ProcessSegment(current, seg)
 			this.dataOutputCond.Signal()
 		case *CmdOnlySegment:
-			this.HandleOption(seg.Opt)
-			if seg.Cmd == CommandTerminate {
+			this.HandleOption(seg.Option)
+			if seg.Command == CommandTerminate {
 				state := this.State()
 				if state == StateActive ||
 					state == StatePeerClosed {
@@ -469,7 +469,7 @@ func (this *Connection) flush() {
 		defer seg.Release()
 
 		seg.Conv = this.conv
-		seg.Cmd = CommandTerminate
+		seg.Command = CommandTerminate
 		this.output.Write(seg)
 		this.output.Flush()
 
@@ -493,11 +493,11 @@ func (this *Connection) flush() {
 	if this.sendingWorker.PingNecessary() || this.receivingWorker.PingNecessary() || current-atomic.LoadUint32(&this.lastPingTime) >= 5000 {
 		seg := NewCmdOnlySegment()
 		seg.Conv = this.conv
-		seg.Cmd = CommandPing
+		seg.Command = CommandPing
 		seg.ReceivinNext = this.receivingWorker.nextNumber
 		seg.SendingNext = this.sendingWorker.firstUnacknowledged
 		if this.State() == StateReadyToClose {
-			seg.Opt = SegmentOptionClose
+			seg.Option = SegmentOptionClose
 		}
 		this.output.Write(seg)
 		this.lastPingTime = current
diff --git a/transport/internet/kcp/receiving.go b/transport/internet/kcp/receiving.go
index 0a9a905b..6fd1f251 100644
--- a/transport/internet/kcp/receiving.go
+++ b/transport/internet/kcp/receiving.go
@@ -253,7 +253,7 @@ func (this *ReceivingWorker) Write(seg Segment) {
 	ackSeg.ReceivingNext = this.nextNumber
 	ackSeg.ReceivingWindow = this.nextNumber + this.windowSize
 	if this.conn.state == StateReadyToClose {
-		ackSeg.Opt = SegmentOptionClose
+		ackSeg.Option = SegmentOptionClose
 	}
 	this.conn.output.Write(ackSeg)
 	this.updated = false
diff --git a/transport/internet/kcp/segment.go b/transport/internet/kcp/segment.go
index 1c8c739e..7a94d9a5 100644
--- a/transport/internet/kcp/segment.go
+++ b/transport/internet/kcp/segment.go
@@ -34,7 +34,7 @@ const (
 
 type DataSegment struct {
 	Conv        uint16
-	Opt         SegmentOption
+	Option      SegmentOption
 	Timestamp   uint32
 	Number      uint32
 	SendingNext uint32
@@ -51,7 +51,7 @@ func NewDataSegment() *DataSegment {
 
 func (this *DataSegment) Bytes(b []byte) []byte {
 	b = serial.Uint16ToBytes(this.Conv, b)
-	b = append(b, byte(CommandData), byte(this.Opt))
+	b = append(b, byte(CommandData), byte(this.Option))
 	b = serial.Uint32ToBytes(this.Timestamp, b)
 	b = serial.Uint32ToBytes(this.Number, b)
 	b = serial.Uint32ToBytes(this.SendingNext, b)
@@ -71,7 +71,7 @@ func (this *DataSegment) Release() {
 
 type AckSegment struct {
 	Conv            uint16
-	Opt             SegmentOption
+	Option          SegmentOption
 	ReceivingWindow uint32
 	ReceivingNext   uint32
 	Count           byte
@@ -99,7 +99,7 @@ func (this *AckSegment) ByteSize() int {
 
 func (this *AckSegment) Bytes(b []byte) []byte {
 	b = serial.Uint16ToBytes(this.Conv, b)
-	b = append(b, byte(CommandACK), byte(this.Opt))
+	b = append(b, byte(CommandACK), byte(this.Option))
 	b = serial.Uint32ToBytes(this.ReceivingWindow, b)
 	b = serial.Uint32ToBytes(this.ReceivingNext, b)
 	b = append(b, this.Count)
@@ -117,8 +117,8 @@ func (this *AckSegment) Release() {
 
 type CmdOnlySegment struct {
 	Conv         uint16
-	Cmd          Command
-	Opt          SegmentOption
+	Command      Command
+	Option       SegmentOption
 	SendingNext  uint32
 	ReceivinNext uint32
 }
@@ -133,7 +133,7 @@ func (this *CmdOnlySegment) ByteSize() int {
 
 func (this *CmdOnlySegment) Bytes(b []byte) []byte {
 	b = serial.Uint16ToBytes(this.Conv, b)
-	b = append(b, byte(this.Cmd), byte(this.Opt))
+	b = append(b, byte(this.Command), byte(this.Option))
 	b = serial.Uint32ToBytes(this.SendingNext, b)
 	b = serial.Uint32ToBytes(this.ReceivinNext, b)
 	return b
@@ -157,7 +157,7 @@ func ReadSegment(buf []byte) (Segment, []byte) {
 	if cmd == CommandData {
 		seg := NewDataSegment()
 		seg.Conv = conv
-		seg.Opt = opt
+		seg.Option = opt
 		if len(buf) < 16 {
 			return nil, nil
 		}
@@ -185,7 +185,7 @@ func ReadSegment(buf []byte) (Segment, []byte) {
 	if cmd == CommandACK {
 		seg := NewAckSegment()
 		seg.Conv = conv
-		seg.Opt = opt
+		seg.Option = opt
 		if len(buf) < 9 {
 			return nil, nil
 		}
@@ -212,8 +212,8 @@ func ReadSegment(buf []byte) (Segment, []byte) {
 
 	seg := NewCmdOnlySegment()
 	seg.Conv = conv
-	seg.Cmd = cmd
-	seg.Opt = opt
+	seg.Command = cmd
+	seg.Option = opt
 
 	if len(buf) < 8 {
 		return nil, nil
diff --git a/transport/internet/kcp/sending.go b/transport/internet/kcp/sending.go
index f3901c33..0871610c 100644
--- a/transport/internet/kcp/sending.go
+++ b/transport/internet/kcp/sending.go
@@ -356,9 +356,9 @@ func (this *SendingWorker) Write(seg Segment) {
 
 	dataSeg.Conv = this.conn.conv
 	dataSeg.SendingNext = this.firstUnacknowledged
-	dataSeg.Opt = 0
+	dataSeg.Option = 0
 	if this.conn.State() == StateReadyToClose {
-		dataSeg.Opt = SegmentOptionClose
+		dataSeg.Option = SegmentOptionClose
 	}
 
 	this.conn.output.Write(dataSeg)