diff --git a/nux/ntp.go b/nux/ntp.go
index e2b5cbf..cc63e0e 100644
--- a/nux/ntp.go
+++ b/nux/ntp.go
@@ -134,21 +134,30 @@ func getTime(host string, version byte, timeout int64) (time.Time, error) {
 	return t, nil
 }
 
+func getTimeout(timeout []int64) int64 {
+	// If the timeout parameter is not provided or the timeout parameter is greater than 0
+	if len(timeout) != 1 {
+		return 5
+	} else {
+		return timeout[0]
+	}
+}
+
 // TimeV returns the "receive time" from the remote NTP server
 // specifed as host.  Use the NTP client mode with the requested
 // version number (2, 3, or 4).
-func NtpTimeV(host string, version byte, timeout int64) (time.Time, error) {
-	return getTime(host, version, timeout)
+func NtpTimeV(host string, version byte, timeout ...int64) (time.Time, error) {
+	return getTime(host, version, getTimeout(timeout))
 }
 
 // Time returns the "receive time" from the remote NTP server
 // specifed as host.  NTP client mode version 4 is used.
-func NtpTime(host string, timeout int64) (time.Time, error) {
-	return getTime(host, 4, timeout)
+func NtpTime(host string, timeout ...int64) (time.Time, error) {
+	return getTime(host, 4, getTimeout(timeout))
 }
 
 // Time returns the "receive time" from the remote NTP server
 // specifed as host.  NTP client mode version 4 is used.
-func NtpTwoTime(host string, timeout int64) (time.Time, time.Time, error) {
-	return getTwoTime(host, 4, timeout)
+func NtpTwoTime(host string, timeout ...int64) (time.Time, time.Time, error) {
+	return getTwoTime(host, 4, getTimeout(timeout))
 }
diff --git a/nux/ntp_test.go b/nux/ntp_test.go
new file mode 100644
index 0000000..a137a13
--- /dev/null
+++ b/nux/ntp_test.go
@@ -0,0 +1,24 @@
+package nux
+
+import (
+	"log"
+	"testing"
+	"time"
+)
+
+func TestNtpTime(t *testing.T) {
+	orgTime := time.Now()
+	log.Println("Begin")
+	serverReciveTime, serverTransmitTime, err := NtpTwoTime("ntp1.aliyun.com", 20)
+	if err != nil {
+		log.Println(err)
+		return
+	}
+	dstTime := time.Now()
+
+	// https://en.wikipedia.org/wiki/Network_Time_Protocol
+	duration := ((serverReciveTime.UnixNano() - orgTime.UnixNano()) + (serverTransmitTime.UnixNano() - dstTime.UnixNano())) / 2
+
+	delta := duration / 1e6 // convert to ms
+	log.Println(delta)
+}