diff --git a/code/linked-list/book/LinkedList.ts b/code/linked-list/book/LinkedList.ts
index 0644c7b..431638a 100644
--- a/code/linked-list/book/LinkedList.ts
+++ b/code/linked-list/book/LinkedList.ts
@@ -4,11 +4,11 @@ import { type LinkedListInterface } from './type';
 
 export default class LinkedList<T> implements LinkedListInterface<T> {
   count: number;
-  head: null | LinkedNode<T>;
+  head: undefined | LinkedNode<T>;
   eqFn: (a: T, b: T) => boolean;
   constructor(eq = defaultEquals) {
     this.count = 0;
-    this.head = null;
+    this.head = undefined;
     this.eqFn = eq;
   }
 
@@ -23,20 +23,40 @@ export default class LinkedList<T> implements LinkedListInterface<T> {
       }
       current.next = node;
     }
-
     this.count++;
   }
 
-  // @ts-ignore
   insert(element: T, position: number) {
-    // @ts-ignore
-    const node = new LinkedListNode(element);
-
-    this.count++;
+    if (position >= 0 && position <= this.count) {
+      const node = new LinkedNode(element);
+      if (position == 0) {
+        let c = this.head;
+        node.next = c;
+        this.head = node;
+      } else {
+        const pre = this.getElementAt(position - 1);
+        if (pre) {
+          const next = pre.next;
+          pre.next = node;
+          node.next = next;
+        }
+      }
+      this.count++;
+      return true;
+    }
     return false;
   }
-  // @ts-ignore
   getElementAt(index: number) {
+    if (index >= 0 && index < this.count) {
+      let current = this.head;
+      for (let i = 0; i < this.count; i++) {
+        if (i === index) {
+          break;
+        }
+        current = current?.next;
+      }
+      return current;
+    }
     return undefined;
   }
 
@@ -50,42 +70,45 @@ export default class LinkedList<T> implements LinkedListInterface<T> {
   }
 
   removeAt(index: number) {
-    if (index >= 0 && index < this.count) {
-      let prev = this.head;
-      let i = 0;
-      while (prev?.next != null) {
-        if (i === index) {
-          break;
-        }
-        prev = prev.next;
-        i++;
+    if (index === 0) {
+      if (typeof this.head !== 'undefined') {
+        let c = this.head;
+        this.head = this.head.next;
+        this.count--;
+        return c.val;
       }
-
-      const target = prev?.next;
-
-      if (prev && prev.next && target) {
-        prev.next = target.next;
+    } else {
+      const prev = this.getElementAt(index - 1);
+      let current = prev?.next;
+      if (prev) {
+        prev.next = current?.next;
+        this.count--;
+        return current?.val;
       }
-      this.count--;
-      return target?.val;
     }
-    return;
+    return undefined;
   }
+
   isEmpty() {
     return this.size() === 0;
   }
   size() {
     return this.count;
   }
+
   toString() {
-    const arr: T[] = [];
-    let c = this.head;
-    while (c?.next !== null) {
-      c?.val && arr.push(c.val);
-      // @ts-ignore
-      c = c?.next;
+    if (!this.head) {
+      return '';
+    }
+    let result = `${this.head?.val}`;
+    let current: LinkedNode<T> | undefined = this.head;
+    for (let i = 1; i < this.count; i++) {
+      current = current?.next;
+      if (current) {
+        result += `,${current.val}`;
+      }
     }
 
-    return arr.join(',');
+    return result;
   }
 }
diff --git a/code/linked-list/book/LinkedNode.ts b/code/linked-list/book/LinkedNode.ts
index 94ac7e6..f4497c2 100644
--- a/code/linked-list/book/LinkedNode.ts
+++ b/code/linked-list/book/LinkedNode.ts
@@ -3,9 +3,9 @@
  */
 export class LinkedNode<T> {
   val: T;
-  next: null | LinkedNode<T>;
+  next: undefined | LinkedNode<T>;
   constructor(v: T) {
     this.val = v;
-    this.next = null;
+    this.next = undefined;
   }
 }
diff --git a/code/linked-list/book/type.ts b/code/linked-list/book/type.ts
index 3f0f180..b51a60a 100644
--- a/code/linked-list/book/type.ts
+++ b/code/linked-list/book/type.ts
@@ -1,3 +1,5 @@
+import { LinkedNode } from "./LinkedNode";
+
 export interface LinkedListInterface<T> {
   /**
    * 添加一个节点
@@ -19,7 +21,7 @@ export interface LinkedListInterface<T> {
    * @param index
    * @returns
    */
-  getElementAt: (index: number) => T | undefined;
+  getElementAt: (index: number) => LinkedNode<T> | undefined;
 
   /**
    * 从链表中移除一个元素
diff --git a/code/linked-list/test/LinkedList.test.ts b/code/linked-list/test/LinkedList.test.ts
index fc45ed7..ae83f91 100644
--- a/code/linked-list/test/LinkedList.test.ts
+++ b/code/linked-list/test/LinkedList.test.ts
@@ -8,231 +8,40 @@ describe('LinkedList', () => {
 
   it('should append node to linked list', () => {
     const linkedList = new LinkedList<number>();
-
-    expect(linkedList.head).toBeNull();
-
+    expect(linkedList.head).toBeUndefined();
     linkedList.push(1);
     linkedList.push(2);
-
     expect(linkedList.toString()).toBe('1,2');
-    // expect(linkedList.tail.next).toBeNull();
   });
 
-  // it('should prepend node to linked list', () => {
-  //   const linkedList = new LinkedList();
-
-  //   linkedList.prepend(2);
-  //   expect(linkedList.head.toString()).toBe('2');
-  //   expect(linkedList.tail.toString()).toBe('2');
-
-  //   linkedList.append(1);
-  //   linkedList.prepend(3);
-
-  //   expect(linkedList.toString()).toBe('3,2,1');
-  // });
-
-  // it('should insert node to linked list', () => {
-  //   const linkedList = new LinkedList();
-
-  //   linkedList.insert(4, 3);
-  //   expect(linkedList.head.toString()).toBe('4');
-  //   expect(linkedList.tail.toString()).toBe('4');
-
-  //   linkedList.insert(3, 2);
-  //   linkedList.insert(2, 1);
-  //   linkedList.insert(1, -7);
-  //   linkedList.insert(10, 9);
-
-  //   expect(linkedList.toString()).toBe('1,4,2,3,10');
-  // });
-
-  // it('should delete node by value from linked list', () => {
-  //   const linkedList = new LinkedList();
-
-  //   expect(linkedList.delete(5)).toBeNull();
-
-  //   linkedList.append(1);
-  //   linkedList.append(1);
-  //   linkedList.append(2);
-  //   linkedList.append(3);
-  //   linkedList.append(3);
-  //   linkedList.append(3);
-  //   linkedList.append(4);
-  //   linkedList.append(5);
-
-  //   expect(linkedList.head.toString()).toBe('1');
-  //   expect(linkedList.tail.toString()).toBe('5');
-
-  //   const deletedNode = linkedList.delete(3);
-
-  //   expect(deletedNode.value).toBe(3);
-  //   expect(linkedList.toString()).toBe('1,1,2,4,5');
-
-  //   linkedList.delete(3);
-  //   expect(linkedList.toString()).toBe('1,1,2,4,5');
-
-  //   linkedList.delete(1);
-  //   expect(linkedList.toString()).toBe('2,4,5');
-
-  //   expect(linkedList.head.toString()).toBe('2');
-  //   expect(linkedList.tail.toString()).toBe('5');
-
-  //   linkedList.delete(5);
-  //   expect(linkedList.toString()).toBe('2,4');
-
-  //   expect(linkedList.head.toString()).toBe('2');
-  //   expect(linkedList.tail.toString()).toBe('4');
-
-  //   linkedList.delete(4);
-  //   expect(linkedList.toString()).toBe('2');
-
-  //   expect(linkedList.head.toString()).toBe('2');
-  //   expect(linkedList.tail.toString()).toBe('2');
-
-  //   linkedList.delete(2);
-  //   expect(linkedList.toString()).toBe('');
-  // });
-
-  // it('should delete linked list tail', () => {
-  //   const linkedList = new LinkedList();
-
-  //   linkedList.append(1);
-  //   linkedList.append(2);
-  //   linkedList.append(3);
-
-  //   expect(linkedList.head.toString()).toBe('1');
-  //   expect(linkedList.tail.toString()).toBe('3');
-
-  //   const deletedNode1 = linkedList.deleteTail();
-
-  //   expect(deletedNode1.value).toBe(3);
-  //   expect(linkedList.toString()).toBe('1,2');
-  //   expect(linkedList.head.toString()).toBe('1');
-  //   expect(linkedList.tail.toString()).toBe('2');
-
-  //   const deletedNode2 = linkedList.deleteTail();
-
-  //   expect(deletedNode2.value).toBe(2);
-  //   expect(linkedList.toString()).toBe('1');
-  //   expect(linkedList.head.toString()).toBe('1');
-  //   expect(linkedList.tail.toString()).toBe('1');
-
-  //   const deletedNode3 = linkedList.deleteTail();
-
-  //   expect(deletedNode3.value).toBe(1);
-  //   expect(linkedList.toString()).toBe('');
-  //   expect(linkedList.head).toBeNull();
-  //   expect(linkedList.tail).toBeNull();
-  // });
-
-  // it('should delete linked list head', () => {
-  //   const linkedList = new LinkedList();
-
-  //   expect(linkedList.deleteHead()).toBeNull();
-
-  //   linkedList.append(1);
-  //   linkedList.append(2);
-
-  //   expect(linkedList.head.toString()).toBe('1');
-  //   expect(linkedList.tail.toString()).toBe('2');
-
-  //   const deletedNode1 = linkedList.deleteHead();
-
-  //   expect(deletedNode1.value).toBe(1);
-  //   expect(linkedList.toString()).toBe('2');
-  //   expect(linkedList.head.toString()).toBe('2');
-  //   expect(linkedList.tail.toString()).toBe('2');
-
-  //   const deletedNode2 = linkedList.deleteHead();
-
-  //   expect(deletedNode2.value).toBe(2);
-  //   expect(linkedList.toString()).toBe('');
-  //   expect(linkedList.head).toBeNull();
-  //   expect(linkedList.tail).toBeNull();
-  // });
-
-  // it('should be possible to store objects in the list and to print them out', () => {
-  //   const linkedList = new LinkedList();
-
-  //   const nodeValue1 = { value: 1, key: 'key1' };
-  //   const nodeValue2 = { value: 2, key: 'key2' };
-
-  //   linkedList.append(nodeValue1).prepend(nodeValue2);
-
-  //   const nodeStringifier = (value) => `${value.key}:${value.value}`;
-
-  //   expect(linkedList.toString(nodeStringifier)).toBe('key2:2,key1:1');
-  // });
-
-  // it('should find node by value', () => {
-  //   const linkedList = new LinkedList();
-
-  //   expect(linkedList.find({ value: 5 })).toBeNull();
-
-  //   linkedList.append(1);
-  //   expect(linkedList.find({ value: 1 })).toBeDefined();
-
-  //   linkedList.append(2).append(3);
-
-  //   const node = linkedList.find({ value: 2 });
-
-  //   expect(node.value).toBe(2);
-  //   expect(linkedList.find({ value: 5 })).toBeNull();
-  // });
-
-  // it('should find node by callback', () => {
-  //   const linkedList = new LinkedList<any>();
-
-  //   linkedList
-  //     .append({ value: 1, key: 'test1' })
-  //     .append({ value: 2, key: 'test2' })
-  //     .append({ value: 3, key: 'test3' });
-
-  //   const node = linkedList.find({
-  //     callback: (value) => value.key === 'test2',
-  //   });
+  it('should removeAt node by index linked list', () => {
+    const linkedList = new LinkedList<number>();
+    linkedList.push(1);
+    linkedList.push(2);
 
-  //   expect(node).toBeDefined();
-  //   expect(node.value.value).toBe(2);
-  //   expect(node.value.key).toBe('test2');
-  //   expect(linkedList.find({ callback: (value) => value.key === 'test5' })).toBeNull();
-  // });
+    linkedList.removeAt(1);
+    expect(linkedList.toString()).toBe('1');
+  });
 
-  // it('should create linked list from array', () => {
-  //   const linkedList = new LinkedList();
-  //   linkedList.fromArray([1, 1, 2, 3, 3, 3, 4, 5]);
 
-  //   expect(linkedList.toString()).toBe('1,1,2,3,3,3,4,5');
-  // });
 
-  // it('should convert to array', () => {
-  //   const linkedList = new LinkedList();
-  //   linkedList.append(1);
-  //   linkedList.append(2);
-  //   linkedList.append(3);
-  //   expect(linkedList.toArray().join(',')).toBe('1,2,3');
-  // });
+  it('should getElementAt by index linked list', () => {
+    const linkedList = new LinkedList<number>();
+    linkedList.push(1);
+    linkedList.push(2);
 
-  // it('should reverse linked list', () => {
-  //   const linkedList = new LinkedList();
+    const v = linkedList.getElementAt(1);
+    expect(v?.val).toBe(2);
+  });
 
-  //   // Add test values to linked list.
-  //   linkedList.append(1).append(2).append(3);
 
-  //   expect(linkedList.toString()).toBe('1,2,3');
-  //   expect(linkedList.head.value).toBe(1);
-  //   expect(linkedList.tail.value).toBe(3);
+  it('should insert by index linked list', () => {
+    const linkedList = new LinkedList<number>();
+    linkedList.push(1);
+    linkedList.push(2);
 
-  //   // Reverse linked list.
-  //   linkedList.reverse();
-  //   expect(linkedList.toString()).toBe('3,2,1');
-  //   expect(linkedList.head.value).toBe(3);
-  //   expect(linkedList.tail.value).toBe(1);
+    linkedList.insert(4, 1);
+    expect(linkedList.toString()).toBe('1,4,2');
+  });
 
-  //   // Reverse linked list back to initial state.
-  //   linkedList.reverse();
-  //   expect(linkedList.toString()).toBe('1,2,3');
-  //   expect(linkedList.head.value).toBe(1);
-  //   expect(linkedList.tail.value).toBe(3);
-  // });
 });
diff --git a/docs/zh/guide/book/linkedList.mdx b/docs/zh/guide/book/linkedList.mdx
deleted file mode 100644
index fbbb6e4..0000000
--- a/docs/zh/guide/book/linkedList.mdx
+++ /dev/null
@@ -1,12 +0,0 @@
-# 第6章 链表
-
-链表是一种物理存储单元上非连续、非顺序的存储结构。数据元素的逻辑顺序通过指针链接实现。链表是由一系列结点组成。
-特点是：添加和删除都比较方便。但是访问比较耗时。
-
-## 种类
-
-链表主要分为以下几种：
-
-- 单向链表
-- 双向链表
-- 循环链表
diff --git a/modern.config.ts b/modern.config.ts
index cf78ebb..19cde3f 100644
--- a/modern.config.ts
+++ b/modern.config.ts
@@ -43,7 +43,7 @@ function getSidebarConfig(lang: 'zh' | 'en') {
           getLink('/guide/book/chap3'),
           getLink('/guide/book/chap4'),
           getLink('/guide/book/chap5'),
-          getLink('/guide/book/linkedList'),
+          getLink('/guide/book/chap6'),
           getLink('/guide/book/recursive'),
           getLink('/guide/book/heap'),
           getLink('/guide/book/chap13'),