diff --git a/tidb-lightning.toml b/tidb-lightning.toml
index e0151ae0c6a97..2d7a4cafd14f5 100644
--- a/tidb-lightning.toml
+++ b/tidb-lightning.toml
@@ -35,8 +35,6 @@ user = "root"
 password = ""
 # PD Server of target cluster
 pd-addr = "127.0.0.1:2379"
-# Uncomment the following line if you want to set sql-mode. You can set it to empty string or any valid sql-mode value supported by tidb
-# sql-mode = ""
 # lightning uses some code of tidb(used as library), and the flag controls it's log level.
 log-level = "error"
 # set tidb session variable to speed up checksum/analyze table.