diff --git a/pkg/exchange/okex/convert.go b/pkg/exchange/okex/convert.go
index f1889bb0a..0551ef684 100644
--- a/pkg/exchange/okex/convert.go
+++ b/pkg/exchange/okex/convert.go
@@ -97,6 +97,10 @@ func convertSubscription(s types.Subscription) (WebsocketSubscription, error) {
 		}, nil
 
 	case types.BookChannel:
+		if s.Options.Depth != types.DepthLevel400 {
+			return WebsocketSubscription{}, fmt.Errorf("%s depth not supported", s.Options.Depth)
+		}
+
 		return WebsocketSubscription{
 			Channel:      ChannelBooks,
 			InstrumentID: toLocalSymbol(s.Symbol),
diff --git a/pkg/exchange/okex/stream_test.go b/pkg/exchange/okex/stream_test.go
index a832767cf..7f85973ad 100644
--- a/pkg/exchange/okex/stream_test.go
+++ b/pkg/exchange/okex/stream_test.go
@@ -48,7 +48,7 @@ func TestStream(t *testing.T) {
 
 	t.Run("book test", func(t *testing.T) {
 		s.Subscribe(types.BookChannel, "BTCUSDT", types.SubscribeOptions{
-			Depth: types.DepthLevel50,
+			Depth: types.DepthLevel400,
 		})
 		s.SetPublicOnly()
 		err := s.Connect(context.Background())
@@ -97,7 +97,7 @@ func TestStream(t *testing.T) {
 
 	t.Run("Subscribe/Unsubscribe test", func(t *testing.T) {
 		s.Subscribe(types.BookChannel, "BTCUSDT", types.SubscribeOptions{
-			Depth: types.DepthLevel50,
+			Depth: types.DepthLevel400,
 		})
 		s.SetPublicOnly()
 		err := s.Connect(context.Background())
@@ -119,7 +119,7 @@ func TestStream(t *testing.T) {
 
 	t.Run("Resubscribe test", func(t *testing.T) {
 		s.Subscribe(types.BookChannel, "BTCUSDT", types.SubscribeOptions{
-			Depth: types.DepthLevel50,
+			Depth: types.DepthLevel400,
 		})
 		s.SetPublicOnly()
 		err := s.Connect(context.Background())
diff --git a/pkg/types/stream.go b/pkg/types/stream.go
index f8aa209e1..aaa9efab5 100644
--- a/pkg/types/stream.go
+++ b/pkg/types/stream.go
@@ -547,6 +547,7 @@ const (
 	DepthLevel20     Depth = "20"
 	DepthLevel50     Depth = "50"
 	DepthLevel200    Depth = "200"
+	DepthLevel400    Depth = "400"
 )
 
 type Speed string