diff --git a/system-variables.md b/system-variables.md
index 379190e5b9c95..b194276b92aa5 100644
--- a/system-variables.md
+++ b/system-variables.md
@@ -1784,6 +1784,16 @@ mysql> SELECT job_info FROM mysql.analyze_jobs ORDER BY end_time DESC LIMIT 1;
 - This variable is renamed from the variable [`tidb_ddl_version`](https://docs-archive.pingcap.com/tidb/v7.6/system-variables#tidb_ddl_version-new-in-v760) that is introduced in v7.6.0. Starting from v8.0.0, `tidb_ddl_version` no longer takes effect.
 - Starting from TiDB v8.5.0, the accelerated table creation feature is enabled by default for newly created clusters, with `tidb_enable_fast_create_table` set to `ON`. For clusters upgraded from v8.4.0 or earlier versions, the default value of `tidb_enable_fast_create_table` remains unchanged.
 
+### tidb_opt_selectivity_factor <span class="version-mark">New in v9.0.0</span>
+
+- Scope: SESSION | GLOBAL
+- Persists to cluster: Yes
+- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes
+- Type: Float
+- Range: `[0, 1]`
+- Default value: `0.8`
+- This variable specifies the pseudo selectivity for the TiDB optimizer. In some cases where the optimizer cannot deduce the selectivity of a predicate from statistics, TiDB optimizer uses this pseudo selectivity value instead. It is **NOT** recommended that you modify this value.
+
 ### tidb_default_string_match_selectivity <span class="version-mark">New in v6.2.0</span>
 
 - Scope: SESSION | GLOBAL