diff --git a/src/evaluate/declaration.ts b/src/evaluate/declaration.ts
index 8b0984e..e687df9 100644
--- a/src/evaluate/declaration.ts
+++ b/src/evaluate/declaration.ts
@@ -38,11 +38,11 @@ export function* VariableDeclarator(
   scope: Scope,
   options: VariableDeclaratorOptions & VariableDeclarationOptions = {},
 ) {
-  const { kind = 'let', hoist = false, onlyBlock = false, feed } = options
+  const { kind = 'var', hoist = false, onlyBlock = false, feed } = options
   if (hoist) {
     if (onlyBlock || kind === 'var') {
       if (node.id.type === 'Identifier') {
-        scope[onlyBlock ? kind : 'var'](node.id.name, onlyBlock ? DEADZONE : undefined)
+        scope[kind](node.id.name, onlyBlock ? DEADZONE : kind === 'var' ? NOINIT : undefined)
       } else {
         yield* pattern(node.id, scope, { kind, hoist, onlyBlock })
       }
diff --git a/src/evaluate/helper.ts b/src/evaluate/helper.ts
index 18aa37f..8622e17 100644
--- a/src/evaluate/helper.ts
+++ b/src/evaluate/helper.ts
@@ -143,9 +143,9 @@ export function createFunc(
     for (let i = 0; i < params.length; i++) {
       const param = params[i]
       if (param.type === 'Identifier') {
-        subScope.let(param.name, args[i])
+        subScope.var(param.name, args[i])
       } else if (param.type === 'RestElement') {
-        yield* RestElement(param, subScope, { kind: 'let', feed: args.slice(i) })
+        yield* RestElement(param, subScope, { kind: 'var', feed: args.slice(i) })
       } else {
         yield* pattern(param, subScope, { feed: args[i] })
       }
diff --git a/src/evaluate/pattern.ts b/src/evaluate/pattern.ts
index 4721478..8585582 100644
--- a/src/evaluate/pattern.ts
+++ b/src/evaluate/pattern.ts
@@ -1,6 +1,6 @@
+import { NOINIT, DEADZONE } from '../share/const'
 import { VarKind } from '../scope/variable'
 import { Identifier } from './identifier'
-import { DEADZONE } from '../share/const'
 import { assign } from '../share/util'
 import { pattern } from './helper'
 import * as estree from 'estree'
@@ -15,7 +15,7 @@ export interface PatternOptions {
 }
 
 export function* ObjectPattern(node: estree.ObjectPattern, scope: Scope, options: PatternOptions = {}) {
-  const { kind = 'let', hoist = false, onlyBlock = false, feed = {} } = options
+  const { kind = 'var', hoist = false, onlyBlock = false, feed = {} } = options
   const fedKeys: string[] = []
   for (let i = 0; i < node.properties.length; i++) {
     const property = node.properties[i]
@@ -24,7 +24,7 @@ export function* ObjectPattern(node: estree.ObjectPattern, scope: Scope, options
         if (property.type === 'Property') {
           const value = property.value
           if (value.type === 'Identifier') {
-            scope[onlyBlock ? kind : 'var'](value.name, onlyBlock ? DEADZONE : undefined)
+            scope[kind](value.name, onlyBlock ? DEADZONE : kind === 'var' ? NOINIT : undefined)
           } else {
             yield* pattern(value, scope, { kind, hoist, onlyBlock })
           }
@@ -64,7 +64,7 @@ export function* ArrayPattern(node: estree.ArrayPattern, scope: Scope, options:
     if (hoist) {
       if (onlyBlock || kind === 'var') {
         if (element.type === 'Identifier') {
-          scope[onlyBlock ? kind : 'var'](element.name, onlyBlock ? DEADZONE : undefined)
+          scope[kind](element.name, onlyBlock ? DEADZONE : kind === 'var' ? NOINIT : undefined)
         } else {
           yield* pattern(element, scope, { kind, hoist, onlyBlock })
         }
@@ -96,7 +96,7 @@ export function* RestElement(node: estree.RestElement, scope: Scope, options: Pa
   if (hoist) {
     if (onlyBlock || kind === 'var') {
       if (arg.type === 'Identifier') {
-        scope[onlyBlock ? kind : 'var'](arg.name, onlyBlock ? DEADZONE : undefined)
+        scope[kind](arg.name, onlyBlock ? DEADZONE : kind === 'var' ? NOINIT : undefined)
       } else {
         yield* pattern(arg, scope, { kind, hoist, onlyBlock })
       }
@@ -116,12 +116,12 @@ export function* RestElement(node: estree.RestElement, scope: Scope, options: Pa
 }
 
 export function* AssignmentPattern(node: estree.AssignmentPattern, scope: Scope, options: PatternOptions = {}) {
-  const { kind = 'let', hoist = false, onlyBlock = false, feed = yield* evaluate(node.right, scope) } = options
+  const { kind = 'var', hoist = false, onlyBlock = false, feed = yield* evaluate(node.right, scope) } = options
   const left = node.left
   if (hoist) {
     if (onlyBlock || kind === 'var') {
       if (left.type === 'Identifier') {
-        scope[onlyBlock ? kind : 'var'](left.name, onlyBlock ? DEADZONE : undefined)
+        scope[kind](left.name, onlyBlock ? DEADZONE : kind === 'var' ? NOINIT : undefined)
       } else {
         yield* pattern(left, scope, { kind, hoist, onlyBlock })
       }
diff --git a/src/evaluate/statement.ts b/src/evaluate/statement.ts
index 56d217c..399cf3b 100644
--- a/src/evaluate/statement.ts
+++ b/src/evaluate/statement.ts
@@ -116,7 +116,7 @@ export function* TryStatement(node: estree.TryStatement, scope: Scope) {
       if (param) {
         if (param.type === 'Identifier') {
           const name = param.name
-          subScope.let(name, err)
+          subScope.var(name, err)
         } else {
           yield* pattern(param, scope, { feed: err })
         }
diff --git a/tests/function.test.ts b/tests/function.test.ts
index 6df3a30..5733976 100644
--- a/tests/function.test.ts
+++ b/tests/function.test.ts
@@ -15,6 +15,18 @@ describe('testing src/index.ts', () => {
 
     expect(interpreter.exports.x).toBeTruthy()
   })
+  it('should redeclare param inside function by var', () => {
+    const interpreter = new Sval()
+    interpreter.run(`
+      a(1)
+      function a(b) {
+        var b = b + 1
+        exports.b = b
+      }
+    `)
+
+    expect(interpreter.exports.b).toBe(2)
+  })
 
   it('should yield generator normally', () => {  
     const interpreter = new Sval()