diff --git a/run.sh b/run.sh
index 52c23ba..d17fd9f 100755
--- a/run.sh
+++ b/run.sh
@@ -36,6 +36,7 @@ do
 			echo "usage: run.sh -s sid -c cycle -w wait_time [-C]"
 			echo "-s: specify serial id of device"
 			echo "-c: specify applist startup cycle"
+			echo "-C: drop cache before start app"
 			echo "-w: specify wait time after app start, before start next app, default 10 s"
 			echo "-k: if to kill all background apps before start app"
 			echo "-T: if check app's mTHP status"