diff --git a/README.md b/README.md
index 079fbee..ff8c36c 100644
--- a/README.md
+++ b/README.md
@@ -222,7 +222,12 @@ nexttrace --tcp --port 443 2001:4860:4860::8888
 # UDP Trace
 nexttrace --udp 1.0.0.1
 
-nexttrace --udp --port 53 1.0.0.1
+# You can specify the target port yourself [here it is 5353], the default is port 33494
+nexttrace --udp --port 5353 1.0.0.1
+
+# For TCP/UDP Trace, you can specify the source port; by default, a fixed random port is used 
+# (if you need to use a different random source port for each packet, please set the ENV variable NEXTTRACE_RANDOMPORT)
+nexttrace --tcp --source-port 14514 www.bing.com
 ```
 
 `NextTrace` also supports some advanced functions, such as ttl control, concurrent probe packet count control, mode switching, etc.
@@ -383,6 +388,8 @@ Arguments:
   -e  --disable-mpls                 Disable MPLS
   -v  --version                      Print version info and exit
   -s  --source                       Use source src_addr for outgoing packets
+      --source-port                  Use source port src_port for outgoing
+                                     packets
   -D  --dev                          Use the following Network Devices as the
                                      source address in outgoing packets
   -z  --send-time                    Set how many [milliseconds] between
diff --git a/README_zh_CN.md b/README_zh_CN.md
index 8aa5d00..9947146 100644
--- a/README_zh_CN.md
+++ b/README_zh_CN.md
@@ -226,14 +226,17 @@ nexttrace --source 204.98.134.56 9.9.9.9
 # TCP SYN Trace
 nexttrace --tcp www.bing.com
 
-# 可以自行指定端口[此处为443]，默认80端口
+# 可以自行指定目标端口[此处为443]，默认80端口
 nexttrace --tcp --port 443 2001:4860:4860::8888
 
 # UDP Trace
 nexttrace --udp 1.0.0.1
 
-# 可以自行指定端口[此处为5353]，默认33494端口
+# 可以自行指定目标端口[此处为5353]，默认33494端口
 nexttrace --udp --port 5353 1.0.0.1
+
+# TCP/UDP Trace 可以自行指定源端口，默认使用随机一个固定的端口(如需每次发包随机使用不同的源端口，请设置`ENV` `NEXTTRACE_RANDOMPORT`)
+nexttrace --tcp --source-port 14514 www.bing.com
 ```
 
 `NextTrace`也同样支持一些进阶功能，如 TTL 控制、并发数控制、模式切换等
@@ -377,6 +380,8 @@ Arguments:
   -e  --disable-mpls                 Disable MPLS
   -v  --version                      Print version info and exit
   -s  --source                       Use source src_addr for outgoing packets
+      --source-port                  Use source port src_port for outgoing
+                                     packets
   -D  --dev                          Use the following Network Devices as the
                                      source address in outgoing packets
   -z  --send-time                    Set how many [milliseconds] between
diff --git a/cmd/cmd.go b/cmd/cmd.go
index 7e63c82..0012f1c 100644
--- a/cmd/cmd.go
+++ b/cmd/cmd.go
@@ -58,7 +58,7 @@ func Excute() {
 	disableMPLS := parser.Flag("e", "disable-mpls", &argparse.Options{Help: "Disable MPLS"})
 	ver := parser.Flag("v", "version", &argparse.Options{Help: "Print version info and exit"})
 	srcAddr := parser.String("s", "source", &argparse.Options{Help: "Use source address src_addr for outgoing packets"})
-	srcPort := parser.Int("", "source-port", &argparse.Options{Help: "Use source port src_port for outgoing packets (TCP and UDP only)"})
+	srcPort := parser.Int("", "source-port", &argparse.Options{Help: "Use source port src_port for outgoing packets"})
 	srcDev := parser.String("D", "dev", &argparse.Options{Help: "Use the following Network Devices as the source address in outgoing packets"})
 	//router := parser.Flag("R", "route", &argparse.Options{Help: "Show Routing Table [Provided By BGP.Tools]"})
 	packetInterval := parser.Int("z", "send-time", &argparse.Options{Default: 50, Help: "Set how many [milliseconds] between sending each packet. Useful when some routers use rate-limit for ICMP messages"})