diff --git a/package.json b/package.json
index 8765d5d0a6d..5719c90f5d9 100644
--- a/package.json
+++ b/package.json
@@ -59,7 +59,6 @@
   "devDependencies": {
     "@chemzqm/tslint-config": "^1.0.17",
     "@types/debounce": "^3.0.0",
-    "@types/diff": "^3.5.1",
     "@types/fast-diff": "^1.1.0",
     "@types/fb-watchman": "^2.0.0",
     "@types/find-up": "^2.1.1",
@@ -84,7 +83,6 @@
     "@chemzqm/neovim": "4.3.24",
     "@chemzqm/tsconfig": "0.0.3",
     "debounce": "^1.2.0",
-    "diff": "^3.5.0",
     "fast-diff": "^1.2.0",
     "fb-watchman": "^2.0.0",
     "find-up": "^3.0.0",
diff --git a/src/__tests__/modules/diff.test.ts b/src/__tests__/modules/diff.test.ts
index 522ca26d46c..bc400e23629 100644
--- a/src/__tests__/modules/diff.test.ts
+++ b/src/__tests__/modules/diff.test.ts
@@ -3,9 +3,9 @@ import { diffLines } from '../../util/diff'
 describe('should get diffLines', () => {
   it('should get diff for added', () => {
     let d = diffLines('1\n2', '1\n2\n3\n4')
-    expect(d.start).toBe(1)
+    expect(d.start).toBe(2)
     expect(d.end).toBe(2)
-    expect(d.replacement).toEqual(['2', '3', '4'])
+    expect(d.replacement).toEqual(['3', '4'])
   })
 
   it('should get diff for added #1', () => {
@@ -42,4 +42,11 @@ describe('should get diffLines', () => {
     expect(d.end).toBe(3)
     expect(d.replacement).toEqual([])
   })
+
+  it('should get diff for remove #1', () => {
+    let d = diffLines('1\n2\n3\n4', '1')
+    expect(d.start).toBe(1)
+    expect(d.end).toBe(4)
+    expect(d.replacement).toEqual([])
+  })
 })
diff --git a/src/util/diff.ts b/src/util/diff.ts
index 8b1ca7c0cd9..fd6b82aa174 100644
--- a/src/util/diff.ts
+++ b/src/util/diff.ts
@@ -1,8 +1,5 @@
-import { diffLines as DiffLines } from 'diff'
 import fastDiff from 'fast-diff'
 import { ChangedLines, ChangeItem } from '../types'
-import { lastIndex } from './array'
-import { trimLast } from './string'
 const logger = require('./logger')('util-diff')
 
 interface Change {
@@ -11,42 +8,36 @@ interface Change {
   newText: string
 }
 
-function getlines(str: string): string[] {
-  let s = trimLast(str, '\n')
-  return s.split('\n')
-}
-
 export function diffLines(from: string, to: string): ChangedLines {
-  let diffs = DiffLines(from, to)
-  let lastIdx = lastIndex(diffs, o => (o.added || o.removed))
-  if (lastIdx == -1) return null
-  let lnum = 0
-  let start = -1
-  let end = -1
-  let lines = []
-  let idx = 0
-  for (let diff of diffs) {
-    if (idx > lastIdx) {
+  let newLines: string[] = to.split('\n')
+  let oldLines: string[] = from.split('\n')
+  let start = 0
+  let end = oldLines.length
+  let oldLen = end
+  let len = newLines.length
+  for (let i = 0; i <= end; i++) {
+    if (newLines[i] !== oldLines[i]) {
+      start = i
       break
     }
-    if (start == -1 && (diff.removed || diff.added)) {
-      start = lnum
-      end = diff.removed ? start + diff.count : start
-      if (diff.added) lines.push(...getlines(diff.value))
-    } else if (diff.removed) {
-      end = lnum + diff.count
-    } else if (diff.added) {
-      end = lnum
-      lines.push(...getlines(diff.value))
-    } else if (start != -1) {
-      lines.push(...getlines(diff.value))
+    if (i == end) {
+      start = end
     }
-    if (!diff.added) {
-      lnum = lnum + diff.count
+  }
+  for (let j = oldLen; j >= 0; j--) {
+    if (oldLines[j - 1] !== newLines[len - (oldLen - j) - 1]) {
+      end = j
+      break
+    }
+    if (j == 0) {
+      end = 0
     }
-    idx = idx + 1
   }
-  return { start, end, replacement: lines }
+  return {
+    start,
+    end,
+    replacement: newLines.slice(start, len - (oldLen - end))
+  }
 }
 
 export function getChangeItem(oldStr: string, newStr: string): ChangeItem {
diff --git a/yarn.lock b/yarn.lock
index 65442b22126..4d7425e1de4 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -130,11 +130,6 @@
   resolved "https://registry.yarnpkg.com/@types/debounce/-/debounce-3.0.0.tgz#ea4290f6e2d7ab99464c93b4a69b843d0993b181"
   integrity sha512-SbehVj+zL0QFTufW3HP/Xvwr/kFWw1sFMLCvmyJdp5Xegbo81sqA2tByWlyeryvSwWBrY4drpLOtGPh0fkxjCQ==
 
-"@types/diff@^3.5.1":
-  version "3.5.1"
-  resolved "https://registry.yarnpkg.com/@types/diff/-/diff-3.5.1.tgz#30253f6e177564ad7da707b1ebe46d3eade71706"
-  integrity sha512-nkT7bd/YM6QRDQjww8PYf0kOj1MvwxQ/WaCinj2Hm1HlL+JqGTm4cDoQeROfiWX/B3SNI1nyLLhLAQpp5sE3hw==
-
 "@types/events@*":
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/@types/events/-/events-1.2.0.tgz#81a6731ce4df43619e5c8c945383b3e62a89ea86"
@@ -1024,7 +1019,7 @@ detect-newline@^2.1.0:
   resolved "https://registry.yarnpkg.com/detect-newline/-/detect-newline-2.1.0.tgz#f41f1c10be4b00e87b5f13da680759f2c5bfd3e2"
   integrity sha1-9B8cEL5LAOh7XxPaaAdZ8sW/0+I=
 
-diff@^3.2.0, diff@^3.5.0:
+diff@^3.2.0:
   version "3.5.0"
   resolved "https://registry.yarnpkg.com/diff/-/diff-3.5.0.tgz#800c0dd1e0a8bfbc95835c202ad220fe317e5a12"
   integrity sha512-A46qtFgd+g7pDZinpnwiRJtxbC1hpgf0uzP3iG89scHk0AUC7A1TGxf5OiiOUv/JMZR8GOt8hL900hV0bOy5xA==