diff --git a/functions-and-operators/bit-functions-and-operators.md b/functions-and-operators/bit-functions-and-operators.md
index 1430d63bcdb6b..3760495c08e54 100644
--- a/functions-and-operators/bit-functions-and-operators.md
+++ b/functions-and-operators/bit-functions-and-operators.md
@@ -6,7 +6,7 @@ aliases: ['/docs/dev/functions-and-operators/bit-functions-and-operators/','/doc
 
 # Bit Functions and Operators
 
-TiDB supports all of the [bit functions and operators](https://dev.mysql.com/doc/refman/5.7/en/bit-functions.html) available in MySQL 5.7.
+TiDB supports all of the [bit functions and operators](https://dev.mysql.com/doc/refman/8.0/en/bit-functions.html) available in MySQL 8.0.
 
 **Bit functions and operators:**
 
@@ -19,3 +19,14 @@ TiDB supports all of the [bit functions and operators](https://dev.mysql.com/doc
 | [^](https://dev.mysql.com/doc/refman/8.0/en/bit-functions.html#operator_bitwise-xor) | Bitwise XOR |
 | [<<](https://dev.mysql.com/doc/refman/8.0/en/bit-functions.html#operator_left-shift) | Left shift |
 | [>>](https://dev.mysql.com/doc/refman/8.0/en/bit-functions.html#operator_right-shift) | Right shift |
+
+## MySQL compatibility
+
+There are some differences between MySQL 8.0 and earlier versions of MySQL in handling bit functions and operators. TiDB aims to follow the behavior of MySQL 8.0.
+
+## Known issues
+
+In the following cases, the query results in TiDB are the same as MySQL 5.7 but different from MySQL 8.0.
+
+- Bitwise operations with binary arguments. For more information, see [#30637](https://github.com/pingcap/tidb/issues/30637).
+- The result of the `BIT_COUNT()` function. For more information, see [#44621](https://github.com/pingcap/tidb/issues/44621).