diff --git a/command-line-flags-for-pd-configuration.md b/command-line-flags-for-pd-configuration.md
index 54685c083ac7b..bf4ed6144d9f2 100644
--- a/command-line-flags-for-pd-configuration.md
+++ b/command-line-flags-for-pd-configuration.md
@@ -102,12 +102,6 @@ PD is configurable using command-line flags and environment variables.
 - The path of the PEM file including the X509 key, used to enable TLS
 - Default: ""
 
-## `--namespace-classifier`
-
-- To specify the namespace classifier used by PD
-- Default: "table"
-- If you use TiKV separately, not in the entire TiDB cluster, it is recommended to configure the value to 'default'.
-
 ## `--metrics-addr`
 
 - The address of Prometheus Pushgateway, which does not push data to Promethus by default.