diff --git a/README.md b/README.md
index 36dfa05..5da5638 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,7 @@ Usage:
 Server OPTION and arguments:
 - `-p port` :set to port binding. couldn't set to 0
 - `-h` or `--help` :print help message.
+- `--progress_bar` :show pretty progress bar
 
 Client option and arguments:
 - `-b` or `--benchmark` :benchmark mode