diff --git a/config/config.go b/config/config.go
index 743262f950df2..13288f7c7c950 100644
--- a/config/config.go
+++ b/config/config.go
@@ -82,7 +82,7 @@ type Config struct {
 	Binlog              Binlog            `toml:"binlog" json:"binlog"`
 	CompatibleKillQuery bool              `toml:"compatible-kill-query" json:"compatible-kill-query"`
 	Plugin              Plugin            `toml:"plugin" json:"plugin"`
-	PessimisticTxn      PessimisticTxn    `toml:"pessimistic-txn" json:"pessimistic_txn"`
+	PessimisticTxn      PessimisticTxn    `toml:"pessimistic-txn" json:"pessimistic-txn"`
 	CheckMb4ValueInUTF8 bool              `toml:"check-mb4-value-in-utf8" json:"check-mb4-value-in-utf8"`
 	// TreatOldVersionUTF8AsUTF8MB4 is use to treat old version table/column UTF8 charset as UTF8MB4. This is for compatibility.
 	// Currently not support dynamic modify, because this need to reload all old version schema.