diff --git a/src/db.rs b/src/db.rs
index ab457b6b..5605fd19 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -8,6 +8,7 @@ use crate::function::char_length::CharLength;
 use crate::function::current_date::CurrentDate;
 use crate::function::lower::Lower;
 use crate::function::numbers::Numbers;
+use crate::function::octet_length::OctetLength;
 use crate::function::upper::Upper;
 use crate::optimizer::heuristic::batch::HepBatchStrategy;
 use crate::optimizer::heuristic::optimizer::HepOptimizer;
@@ -61,6 +62,7 @@ impl DataBaseBuilder {
             builder.register_scala_function(CharLength::new("character_length".to_lowercase()));
         builder = builder.register_scala_function(CurrentDate::new());
         builder = builder.register_scala_function(Lower::new());
+        builder = builder.register_scala_function(OctetLength::new());
         builder = builder.register_scala_function(Upper::new());
         builder = builder.register_table_function(Numbers::new());
         builder
diff --git a/src/function/char_length.rs b/src/function/char_length.rs
index 6cf0c100..817f591a 100644
--- a/src/function/char_length.rs
+++ b/src/function/char_length.rs
@@ -43,7 +43,7 @@ impl ScalarFunctionImpl for CharLength {
         }
         let mut length: u64 = 0;
         if let DataValue::Utf8 { value, ty, unit } = &mut value {
-            length = value.len() as u64;
+            length = value.chars().count() as u64;
         }
         Ok(DataValue::UInt64(length))
     }
diff --git a/src/function/mod.rs b/src/function/mod.rs
index 6c660c57..7930e807 100644
--- a/src/function/mod.rs
+++ b/src/function/mod.rs
@@ -2,4 +2,5 @@ pub(crate) mod char_length;
 pub(crate) mod current_date;
 pub(crate) mod lower;
 pub(crate) mod numbers;
+pub(crate) mod octet_length;
 pub(crate) mod upper;
diff --git a/src/function/octet_length.rs b/src/function/octet_length.rs
new file mode 100644
index 00000000..b712ee3c
--- /dev/null
+++ b/src/function/octet_length.rs
@@ -0,0 +1,63 @@
+use crate::catalog::ColumnRef;
+use crate::errors::DatabaseError;
+use crate::expression::function::scala::FuncMonotonicity;
+use crate::expression::function::scala::ScalarFunctionImpl;
+use crate::expression::function::FunctionSummary;
+use crate::expression::ScalarExpression;
+use crate::types::tuple::Tuple;
+use crate::types::value::DataValue;
+use crate::types::LogicalType;
+use serde::Deserialize;
+use serde::Serialize;
+use sqlparser::ast::CharLengthUnits;
+use std::sync::Arc;
+
+#[derive(Debug, Serialize, Deserialize)]
+pub(crate) struct OctetLength {
+    summary: FunctionSummary,
+}
+
+impl OctetLength {
+    pub(crate) fn new() -> Arc<Self> {
+        let function_name = "octet_length".to_lowercase();
+        let arg_types = vec![LogicalType::Varchar(None, CharLengthUnits::Characters)];
+        Arc::new(Self {
+            summary: FunctionSummary {
+                name: function_name,
+                arg_types,
+            },
+        })
+    }
+}
+
+#[typetag::serde]
+impl ScalarFunctionImpl for OctetLength {
+    #[allow(unused_variables, clippy::redundant_closure_call)]
+    fn eval(
+        &self,
+        exprs: &[ScalarExpression],
+        tuples: Option<(&Tuple, &[ColumnRef])>,
+    ) -> Result<DataValue, DatabaseError> {
+        let mut value = exprs[0].eval(tuples)?;
+        if !matches!(value.logical_type(), LogicalType::Varchar(_, _)) {
+            value = value.cast(&LogicalType::Varchar(None, CharLengthUnits::Characters))?;
+        }
+        let mut length: u64 = 0;
+        if let DataValue::Utf8 { value, ty, unit } = &mut value {
+            length = value.len() as u64;
+        }
+        Ok(DataValue::UInt64(length))
+    }
+
+    fn monotonicity(&self) -> Option<FuncMonotonicity> {
+        todo!()
+    }
+
+    fn return_type(&self) -> &LogicalType {
+        &LogicalType::Varchar(None, CharLengthUnits::Characters)
+    }
+
+    fn summary(&self) -> &FunctionSummary {
+        &self.summary
+    }
+}
diff --git a/tests/slt/sql_2016/E021_04.slt b/tests/slt/sql_2016/E021_04.slt
index ac401405..8d4842b5 100644
--- a/tests/slt/sql_2016/E021_04.slt
+++ b/tests/slt/sql_2016/E021_04.slt
@@ -5,8 +5,17 @@ SELECT CHARACTER_LENGTH ( 'foo' )
 ----
 3
 
-
 query I
 SELECT CHAR_LENGTH ( 'foo' )
 ----
 3
+
+query I
+SELECT CHARACTER_LENGTH ( '测试' )
+----
+2
+
+query I
+SELECT CHAR_LENGTH ( '测试' )
+----
+2
diff --git a/tests/slt/sql_2016/E021_05.slt b/tests/slt/sql_2016/E021_05.slt
index e29fffa7..a40733ff 100644
--- a/tests/slt/sql_2016/E021_05.slt
+++ b/tests/slt/sql_2016/E021_05.slt
@@ -1,8 +1,11 @@
-# E021-05: OCTET_LENGTH function
+#E021-05: OCTET_LENGTH function
 
-# TODO: OCTET_LENGTH()
+query I
+SELECT OCTET_LENGTH ( 'foo' )
+----
+3
 
-# query I
-# SELECT OCTET_LENGTH ( 'foo' )
-# ----
-# 3
+query I
+SELECT OCTET_LENGTH ( '测试' )
+----
+6