diff --git a/pessimistic-transaction.md b/pessimistic-transaction.md
index b759d2af95854..b2bfc808f7f7c 100644
--- a/pessimistic-transaction.md
+++ b/pessimistic-transaction.md
@@ -111,7 +111,9 @@ Pessimistic transactions in TiDB behave similarly to those in MySQL. See the min
 
 2. TiDB does not support `SELECT LOCK IN SHARE MODE`.
 
-    When `SELECT LOCK IN SHARE MODE` is executed, it has the same effect as that without the lock, so the read or write operation of other transactions is not blocked.
+    TiDB does not support the `SELECT LOCK IN SHARE MODE` syntax by default. You can enable [`tidb_enable_noop_functions`](/system-variables.md#tidb_enable_noop_functions-new-in-v40) to make TiDB compatible with the `SELECT LOCK IN SHARE MODE` syntax. Executing `SELECT LOCK IN SHARE MODE` has the same effect as that without the lock, so it does not block read or write operations of other transactions.
+
+    Starting from v8.3.0, TiDB supports using the [`tidb_enable_shared_lock_promotion`](/system-variables.md#tidb_enable_shared_lock_promotion-new-in-v830) system variable to enable the `SELECT LOCK IN SHARE MODE` statement to add locks. However, note that the lock added at this time is not a true shared lock, but an exclusive lock, which is consistent with `SELECT FOR UPDATE`. If you want to block writes to prevent data from being modified by write transactions in parallel during reads while keeping TiDB compatible with the `SELECT LOCK IN SHARE MODE` syntax, you can enable this variable. Enabling this variable takes effect on the `SELECT LOCK IN SHARE MODE` statement, regardless of whether [`tidb_enable_noop_functions`](/system-variables.md#tidb_enable_noop_functions-new-in-v40) is enabled or not.
 
 3. DDL may result in failure of the pessimistic transaction commit.
 
diff --git a/system-variables.md b/system-variables.md
index c6c7c9171fc6b..9bc7eb04aec2f 100644
--- a/system-variables.md
+++ b/system-variables.md
@@ -2567,6 +2567,16 @@ mysql> SELECT job_info FROM mysql.analyze_jobs ORDER BY end_time DESC LIMIT 1;
 - Value options: `OFF`, `ON`
 - This variable controls whether TiDB enables chunk objects cache. If the value is `ON`, TiDB prefers to use the cached chunk object and only requests from the system if the requested object is not in the cache. If the value is `OFF`, TiDB requests chunk objects from the system directly.
 
+### tidb_enable_shared_lock_promotion <span class="version-mark">New in v8.3.0</span>
+
+- Scope: SESSION | 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 enable the feature of upgrading shared locks to exclusive locks. TiDB does not support `SELECT LOCK IN SHARE MODE` by default. When the variable value is `ON`, TiDB tries to upgrade the `SELECT LOCK IN SHARE MODE` statement to `SELECT FOR UPDATE` and add a pessimistic lock. The default value of this variable is `OFF`, which means that the feature of upgrading shared locks to exclusive locks is disabled.
+- Enabling this variable takes effect on the `SELECT LOCK IN SHARE MODE` statement, regardless of whether [`tidb_enable_noop_functions`](/system-variables.md#tidb_enable_noop_functions-new-in-v40) is enabled or not.
+
 ### tidb_enable_slow_log
 
 > **Note:**