diff --git a/readme.md b/readme.md
index af1095a..07a9e25 100644
--- a/readme.md
+++ b/readme.md
@@ -47,6 +47,8 @@ $ tproxy --help
 Usage of tproxy:
   -d duration
     	the delay to relay packets
+  -down int
+    	Downward speed limit(bytes/second)
   -l string
     	Local address to listen on (default "localhost")
   -p int
@@ -57,6 +59,8 @@ Usage of tproxy:
   -s	Enable statistics
   -t string
     	The type of protocol, currently support http2, grpc, redis and mongodb
+  -up int
+    	Upward speed limit(bytes/second)
 ```
 
 ## Examples