diff --git a/README.md b/README.md
index 5876f2b4f..1f86a9203 100644
--- a/README.md
+++ b/README.md
@@ -234,6 +234,7 @@ spark.serializer org.apache.spark.serializer.KryoSerializer
 
 # celeborn master
 spark.celeborn.master.endpoints clb-1:9097,clb-2:9097,clb-3:9097
+# This is not necessary if your Spark external shuffle service is Spark 3.1 or newer
 spark.shuffle.service.enabled false
 
 # options: hash, sort
diff --git a/docs/deploy.md b/docs/deploy.md
index b618d8e5c..b91f74ced 100644
--- a/docs/deploy.md
+++ b/docs/deploy.md
@@ -167,6 +167,7 @@ spark.serializer org.apache.spark.serializer.KryoSerializer
 
 # celeborn master
 spark.celeborn.master.endpoints clb-1:9097,clb-2:9097,clb-3:9097
+# This is not necessary if your Spark external shuffle service is Spark 3.1 or newer
 spark.shuffle.service.enabled false
 
 # options: hash, sort
diff --git a/docs/developers/glutensupport.md b/docs/developers/glutensupport.md
index d3b7b01df..3879e353f 100644
--- a/docs/developers/glutensupport.md
+++ b/docs/developers/glutensupport.md
@@ -47,6 +47,7 @@ spark.celeborn.master.endpoints clb-master:9097
 spark.celeborn.client.push.replicate.enabled true
 
 spark.celeborn.client.spark.shuffle.writer hash
+# This is not necessary if your Spark external shuffle service is Spark 3.1 or newer
 spark.shuffle.service.enabled false
 spark.sql.adaptive.localShuffleReader.enabled false