diff --git a/system-variables.md b/system-variables.md
index 1555a6ceb02e6..51632f9668508 100644
--- a/system-variables.md
+++ b/system-variables.md
@@ -2164,6 +2164,16 @@ Assume that you have a cluster with 4 TiDB nodes and multiple TiKV nodes. In thi
 - Default value: `ON`. Before v8.3.0, the default value is `OFF`.
 - This variable controls whether to enable TiDB to collect `PREDICATE COLUMNS`. After enabling the collection, if you disable it, the information of previously collected `PREDICATE COLUMNS` is cleared. For details, see [Collect statistics on some columns](/statistics.md#collect-statistics-on-some-columns).
 
+### tidb_enable_connection_event_log <span class="version-mark">New in v8.5.8 and v9.0.0</span>
+
+- Scope: GLOBAL
+- Persists to cluster: Yes
+- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No
+- Type: Boolean
+- Default value: `OFF`
+- This variable controls whether to write successful client login and logout events to the TiDB log.
+- If your workload frequently creates and closes connections, enabling this variable can generate a large number of log entries.
+
 ### tidb_enable_enhanced_security
 
 - Scope: NONE