diff --git a/examples/percent.ast b/examples/percent.ast
new file mode 100644
index 0000000..edc1977
--- /dev/null
+++ b/examples/percent.ast
@@ -0,0 +1,5 @@
+let a = 7
+let b = a % 3
+print("b=", b)
+a %= 4
+print("a=", a)
\ No newline at end of file
diff --git a/src/ast/expr.rs b/src/ast/expr.rs
index 87772d5..d04b882 100644
--- a/src/ast/expr.rs
+++ b/src/ast/expr.rs
@@ -106,6 +106,7 @@ pub enum BinaryOp {
     Sub,
     Mul,
     Div,
+    Mod,
 
     Greater,
     GreaterEqual,
@@ -129,4 +130,5 @@ pub enum AssignOp {
     MinusEqual, // -=
     StarEqual,  // *=
     SlashEqual, // /=
+    PercentEqual, // %=
 }
diff --git a/src/interpreter/interpreter.rs b/src/interpreter/interpreter.rs
index 5bd707a..bc209bd 100644
--- a/src/interpreter/interpreter.rs
+++ b/src/interpreter/interpreter.rs
@@ -314,6 +314,13 @@ impl Interpreter {
                             token: None,
                         }),
                     },
+                    crate::ast::expr::BinaryOp::Mod => match (l,r) {
+                        (Value::Number(a), Value::Number(b)) => Ok(Value::Number(a%b)),
+                        _ => Err(RuntimeError::RuntimeError {
+                            message: "Invalid '%' operands".to_string(),
+                            token: None,
+                        }),
+                    },
                     crate::ast::expr::BinaryOp::Greater => Ok(Value::Bool(self.as_number(&l)? > self.as_number(&r)?)),
                     crate::ast::expr::BinaryOp::GreaterEqual => Ok(Value::Bool(self.as_number(&l)? >= self.as_number(&r)?)),
                     crate::ast::expr::BinaryOp::Less => Ok(Value::Bool(self.as_number(&l)? < self.as_number(&r)?)),
@@ -443,6 +450,11 @@ impl Interpreter {
                 let right_num = self.as_number(&right)?;
                 Ok(Value::Number(left_num / right_num))
             }
+            AssignOp::PercentEqual => {
+                let left_num = self.as_number(&left)?;
+                let right_num = self.as_number(&right)?;
+                Ok(Value::Number(left_num % right_num))
+            }
         }
     }
 
diff --git a/src/lexer/lexer.rs b/src/lexer/lexer.rs
index 508a0a3..5a9c36a 100644
--- a/src/lexer/lexer.rs
+++ b/src/lexer/lexer.rs
@@ -96,6 +96,14 @@ impl Lexer {
                 }
             }
 
+            '%' => {
+                if self.match_char('=') {
+                    TokenKind::PercentEqual
+                } else {
+                    TokenKind::Percent
+                }
+            }
+
             '!' => {
                 if self.match_char('=') {
                     TokenKind::BangEqual
diff --git a/src/lexer/token.rs b/src/lexer/token.rs
index 4d7f75d..4fb196b 100644
--- a/src/lexer/token.rs
+++ b/src/lexer/token.rs
@@ -9,14 +9,14 @@ pub enum TokenKind {
     Colon,
 
     // 运算符
-    Plus, Minus, Star, Slash,
+    Plus, Minus, Star, Slash, Percent,
     Bang,
     Equal,
     Greater, GreaterEqual,
     Less, LessEqual,
     EqualEqual, BangEqual,
     AndAnd, OrOr,
-    PlusEqual, MinusEqual, StarEqual, SlashEqual,
+    PlusEqual, MinusEqual, StarEqual, SlashEqual, PercentEqual,
 
     // 字面量
     Identifier(String),
diff --git a/src/parser/parser.rs b/src/parser/parser.rs
index a7c1b62..bcf18cf 100644
--- a/src/parser/parser.rs
+++ b/src/parser/parser.rs
@@ -212,6 +212,8 @@ impl Parser {
             Some(AssignOp::StarEqual)
         } else if self.match_kind(&[TokenKind::SlashEqual]) {
             Some(AssignOp::SlashEqual)
+        } else if self.match_kind(&[TokenKind::PercentEqual]) {
+            Some(AssignOp::PercentEqual)
         } else {
             None
         };
@@ -324,10 +326,11 @@ impl Parser {
     fn factor(&mut self) -> Expr {
         let mut expr = self.unary();
 
-        while self.match_kind(&[TokenKind::Star, TokenKind::Slash]) {
+        while self.match_kind(&[TokenKind::Star, TokenKind::Slash, TokenKind::Percent]) {
             let op = match self.previous().kind {
                 TokenKind::Star => BinaryOp::Mul,
                 TokenKind::Slash => BinaryOp::Div,
+                TokenKind::Percent => BinaryOp::Mod,
                 _ => unreachable!(),
             };
             let right = self.unary();