diff --git a/docs/en/API-reference.md b/docs/en/API-reference.md
index a4e97c914..8dd7d7979 100644
--- a/docs/en/API-reference.md
+++ b/docs/en/API-reference.md
@@ -514,3 +514,9 @@ plugin [`MinMax`](./Plugin.md#minmax)
 `.calendar` to display calendar time
 
 plugin [`Calendar`](./Plugin.md#calendar)
+
+### UpdateLocale
+
+`.updateLocale` to update a locale's properties
+
+plugin [`UpdateLocale`](./Plugin.md#updateLocale)
diff --git a/docs/en/I18n.md b/docs/en/I18n.md
index 045cb8c1e..401063aaf 100644
--- a/docs/en/I18n.md
+++ b/docs/en/I18n.md
@@ -77,7 +77,9 @@ dayjs()
 
 ## Customize
 
-You could create your own locale.
+You could update locale config via plugin [`UpdateLocale`](./Plugin.md#updateLocale)
+
+You could also create your own locale.
 
 Feel free to open a pull request to share your locale.
 
diff --git a/docs/en/Plugin.md b/docs/en/Plugin.md
index cc9688951..c8ba4fc7b 100644
--- a/docs/en/Plugin.md
+++ b/docs/en/Plugin.md
@@ -442,6 +442,19 @@ dayjs().calendar(null, {
 })
 ```
 
+### UpdateLocale
+
+- UpdateLocale adds `.updateLocale` API to update a locale's properties.
+
+```javascript
+import updateLocale from 'dayjs/plugin/updateLocale'
+dayjs.extend(updateLocale)
+
+dayjs.updateLocale('en', {
+  months : String[]
+})
+```
+
 ## Customize
 
 You could build your own Day.js plugin to meet different needs.
diff --git a/docs/es-es/API-reference.md b/docs/es-es/API-reference.md
index 57b3b42d5..be0f30029 100644
--- a/docs/es-es/API-reference.md
+++ b/docs/es-es/API-reference.md
@@ -514,3 +514,9 @@ plugin [`MinMax`](./Plugin.md#minmax)
 `.calendar` to display calendar time
 
 plugin [`Calendar`](./Plugin.md#calendar)
+
+### UpdateLocale
+
+`.updateLocale` to update a locale's properties
+
+plugin [`UpdateLocale`](./Plugin.md#updateLocale)
diff --git a/docs/es-es/I18n.md b/docs/es-es/I18n.md
index 551f38787..989269708 100644
--- a/docs/es-es/I18n.md
+++ b/docs/es-es/I18n.md
@@ -81,7 +81,9 @@ dayjs()
 
 ## Personalización
 
-You could create your own locale.
+You could update locale config via plugin [`UpdateLocale`](./Plugin.md#updateLocale)
+
+You could also create your own locale.
 
 Feel free to open a pull request to share your locale.
 
diff --git a/docs/es-es/Plugin.md b/docs/es-es/Plugin.md
index 7d44c3ad9..e5a7c1469 100644
--- a/docs/es-es/Plugin.md
+++ b/docs/es-es/Plugin.md
@@ -438,6 +438,19 @@ dayjs().calendar(null, {
 })
 ```
 
+### UpdateLocale
+
+- UpdateLocale adds `.updateLocale` API to update a locale's properties.
+
+```javascript
+import updateLocale from 'dayjs/plugin/updateLocale'
+dayjs.extend(updateLocale)
+
+dayjs.updateLocale('en', {
+  months : String[]
+})
+```
+
 ## Personalización
 
 Puedes construir tu propio complemento de Day.js para cubrir tus necesidades.
diff --git a/docs/ja/API-reference.md b/docs/ja/API-reference.md
index 8a1152c16..0eba8f216 100644
--- a/docs/ja/API-reference.md
+++ b/docs/ja/API-reference.md
@@ -514,3 +514,9 @@ UTC でパースや表示をしたい場合は、[`UTC`](./Plugin.md#utc)プラ
 `.calendar`で与えた日付のカレンダー上の情報が得られます。
 
 プラグイン [`Calendar`](./Plugin.md#calendar)
+
+### UpdateLocale
+
+`.updateLocale` to update a locale's properties
+
+plugin [`UpdateLocale`](./Plugin.md#updateLocale)
diff --git a/docs/ja/I18n.md b/docs/ja/I18n.md
index 70f013500..a0dab94f0 100644
--- a/docs/ja/I18n.md
+++ b/docs/ja/I18n.md
@@ -77,6 +77,8 @@ dayjs()
 
 ## カスタマイズ
 
+You could update locale config via plugin [`UpdateLocale`](./Plugin.md#updateLocale)
+
 独自のロケールを作成することもできます。
 
 あなたのプラグインを共有する pull request を是非送ってみてください。
diff --git a/docs/ja/Plugin.md b/docs/ja/Plugin.md
index d0f4a7a23..b8e7580e4 100644
--- a/docs/ja/Plugin.md
+++ b/docs/ja/Plugin.md
@@ -447,6 +447,19 @@ dayjs().calendar(null, {
 })
 ```
 
+### UpdateLocale
+
+- UpdateLocale adds `.updateLocale` API to update a locale's properties.
+
+```javascript
+import updateLocale from 'dayjs/plugin/updateLocale'
+dayjs.extend(updateLocale)
+
+dayjs.updateLocale('en', {
+  months : String[]
+})
+```
+
 ## カスタマイズ
 
 さまざまなニーズに合わせて独自の Day.js プラグインを構築することができます。
diff --git a/docs/ko/API-reference.md b/docs/ko/API-reference.md
index e15ffafd9..70cb5d67d 100644
--- a/docs/ko/API-reference.md
+++ b/docs/ko/API-reference.md
@@ -513,3 +513,9 @@ plugin [`MinMax`](./Plugin.md#minmax)
 `.calendar` to display calendar time
 
 plugin [`Calendar`](./Plugin.md#calendar)
+
+### UpdateLocale
+
+`.updateLocale` to update a locale's properties
+
+plugin [`UpdateLocale`](./Plugin.md#updateLocale)
diff --git a/docs/ko/I18n.md b/docs/ko/I18n.md
index 421b05295..5df968cdc 100644
--- a/docs/ko/I18n.md
+++ b/docs/ko/I18n.md
@@ -77,6 +77,8 @@ dayjs()
 
 ## Customize
 
+You could update locale config via plugin [`UpdateLocale`](./Plugin.md#updateLocale)
+
 당신만의 locale을 만들 수 있습니다.
 
 locale을 공휴하기위해 풀 리퀘스트를 여십시오.
diff --git a/docs/ko/Plugin.md b/docs/ko/Plugin.md
index dba61fdc6..90a9e3423 100644
--- a/docs/ko/Plugin.md
+++ b/docs/ko/Plugin.md
@@ -439,6 +439,19 @@ dayjs().calendar(null, {
 })
 ```
 
+### UpdateLocale
+
+- UpdateLocale adds `.updateLocale` API to update a locale's properties.
+
+```javascript
+import updateLocale from 'dayjs/plugin/updateLocale'
+dayjs.extend(updateLocale)
+
+dayjs.updateLocale('en', {
+  months : String[]
+})
+```
+
 ## Customize
 
 다양한 요구를 충족하기위해 자신만의 Day.js 플러그인을 만들 수 있습니다.
diff --git a/docs/pt-br/API-reference.md b/docs/pt-br/API-reference.md
index 23cb01dac..18c165e81 100644
--- a/docs/pt-br/API-reference.md
+++ b/docs/pt-br/API-reference.md
@@ -512,3 +512,9 @@ plugin [`MinMax`](./Plugin.md#minmax)
 `.calendar` to display calendar time
 
 plugin [`Calendar`](./Plugin.md#calendar)
+
+### UpdateLocale
+
+`.updateLocale` to update a locale's properties
+
+plugin [`UpdateLocale`](./Plugin.md#updateLocale)
diff --git a/docs/pt-br/I18n.md b/docs/pt-br/I18n.md
index f072f95e4..4a383ecf2 100644
--- a/docs/pt-br/I18n.md
+++ b/docs/pt-br/I18n.md
@@ -77,6 +77,8 @@ dayjs()
 
 ## Customizar
 
+You could update locale config via plugin [`UpdateLocale`](./Plugin.md#updateLocale)
+
 Você pode criar o seu próprio _locale_.
 
 Sinta-se a vontade para abrir uma pull request e compartilhar sua _locale_.
diff --git a/docs/pt-br/Plugin.md b/docs/pt-br/Plugin.md
index 22ebe9e8a..8e16f5f58 100644
--- a/docs/pt-br/Plugin.md
+++ b/docs/pt-br/Plugin.md
@@ -438,6 +438,19 @@ dayjs().calendar(null, {
 })
 ```
 
+### UpdateLocale
+
+- UpdateLocale adds `.updateLocale` API to update a locale's properties.
+
+```javascript
+import updateLocale from 'dayjs/plugin/updateLocale'
+dayjs.extend(updateLocale)
+
+dayjs.updateLocale('en', {
+  months : String[]
+})
+```
+
 ## Customizar
 
 Você também pode construir seu próprio plugin Day.js para diferentes necessidades.
diff --git a/docs/zh-cn/API-reference.md b/docs/zh-cn/API-reference.md
index d5cd5753d..02465a8a1 100644
--- a/docs/zh-cn/API-reference.md
+++ b/docs/zh-cn/API-reference.md
@@ -564,3 +564,9 @@ plugin [`MinMax`](./Plugin.md#minmax)
 `.calendar` 来显示日历时间
 
 plugin [`Calendar`](./Plugin.md#calendar)
+
+### 更新语言配置
+
+`.updateLocale` 来更新语言配置的属性
+
+plugin [`UpdateLocale`](./Plugin.md#updateLocale)
diff --git a/docs/zh-cn/I18n.md b/docs/zh-cn/I18n.md
index ca9ebf702..55b4aa108 100644
--- a/docs/zh-cn/I18n.md
+++ b/docs/zh-cn/I18n.md
@@ -77,7 +77,9 @@ dayjs()
 
 ## 自定义
 
-你可以根据需要自由的编写一个 Day.js 语言配置
+你可以使用 [`UpdateLocale`](./Plugin.md#updateLocale) 插件来更新语言配置
+
+你还可以根据需要自由的编写一个 Day.js 语言配置
 
 同时欢迎提交 PR 与大家分享你的语言配置
 
@@ -93,6 +95,20 @@ const localeObject = {
   months: 'Enero_Febrero ... '.split('_'), // 月份 Array
   monthsShort: 'Jan_F'.split('_'), // 可选, 短的月份 Array, 如果没提供则使用前三个字符
   ordinal: n => `${n}º`, // 序号生成工厂函数 Function (number) => return number + output
+  formats: {
+    // 时间日期格式 - 长
+    LTS: 'h:mm:ss A',
+    LT: 'h:mm A',
+    L: 'MM/DD/YYYY',
+    LL: 'MMMM D, YYYY',
+    LLL: 'MMMM D, YYYY h:mm A',
+    LLLL: 'dddd, MMMM D, YYYY h:mm A',
+    // 时间日期格式 - 短
+    l: 'D/M/YYYY',
+    ll: 'D MMM, YYYY',
+    lll: 'D MMM, YYYY h:mm A',
+    llll: 'ddd, MMM D, YYYY h:mm A'
+  },
   relativeTime: {
     // 相对时间, %s %d 不用翻译
     future: 'in %s', // e.g. in 2 hours, %s been replaced with 2hours
diff --git a/docs/zh-cn/Plugin.md b/docs/zh-cn/Plugin.md
index 57838c742..89bdf56ce 100644
--- a/docs/zh-cn/Plugin.md
+++ b/docs/zh-cn/Plugin.md
@@ -441,6 +441,19 @@ dayjs().calendar(null, {
 })
 ```
 
+### UpdateLocale
+
+- UpdateLocale 增加了 `.updateLocale` API 来更新语言配置的属性。
+
+```javascript
+import updateLocale from 'dayjs/plugin/updateLocale'
+dayjs.extend(updateLocale)
+
+dayjs.updateLocale('en', {
+  months : String[]
+})
+```
+
 ## 自定义
 
 你可以根据需要自由的编写一个 Day.js 插件
diff --git a/src/plugin/updateLocale/index.js b/src/plugin/updateLocale/index.js
new file mode 100644
index 000000000..7126f7e1f
--- /dev/null
+++ b/src/plugin/updateLocale/index.js
@@ -0,0 +1,13 @@
+export default (option, Dayjs, dayjs) => {
+  dayjs.updateLocale = function (locale, customConfig) {
+    const localeList = dayjs.Ls
+    const localeConfig = localeList[locale]
+    if (!localeConfig) return
+    const customConfigKeys = customConfig ? Object.keys(customConfig) : []
+    customConfigKeys.forEach((c) => {
+      localeConfig[c] = customConfig[c]
+    })
+    return localeConfig // eslint-disable-line consistent-return
+  }
+}
+
diff --git a/test/plugin/updateLocale.test.js b/test/plugin/updateLocale.test.js
new file mode 100644
index 000000000..ecbcbd41c
--- /dev/null
+++ b/test/plugin/updateLocale.test.js
@@ -0,0 +1,71 @@
+import MockDate from 'mockdate'
+import moment from 'moment'
+import dayjs from '../../src'
+import updateLocale from '../../src/plugin/updateLocale'
+import localizedFormat from '../../src/plugin/localizedFormat'
+import '../../src/locale/zh-cn'
+
+dayjs.extend(updateLocale)
+dayjs.extend(localizedFormat)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+const newLocale = {
+  months: new Array(12).fill('testMonth'),
+  formats: { // formats for dayjs and longDateFormat for momentjs
+    LT: '[testFormat]'
+  },
+  longDateFormat: {
+    LT: '[testFormat]'
+  }
+}
+
+const formatString = 'MMMM LT'
+
+describe('Update locale', () => {
+  it('Invalid argument', () => {
+    const result = dayjs.updateLocale('InvalidLocaleName', {})
+    expect(result)
+      .toEqual(undefined)
+    expect(dayjs().format(formatString))
+      .toEqual(moment().format(formatString))
+  })
+
+  it('Return value', () => {
+    const result1 = dayjs.updateLocale('en')
+    expect(typeof result1).toEqual('object')
+    const result2 = dayjs.updateLocale('en', {})
+    expect(typeof result2).toEqual('object')
+    const result3 = dayjs.updateLocale('en', newLocale)
+    expect(typeof result3).toEqual('object')
+  })
+
+  it('Update build-in en locale', () => {
+    moment.updateLocale('en', newLocale)
+    dayjs.updateLocale('en', newLocale)
+
+    expect(dayjs().format(formatString))
+      .toEqual('testMonth testFormat')
+
+    expect(dayjs().format(formatString))
+      .toEqual(moment().format(formatString))
+  })
+
+  it('Update imported zh-cn locale', () => {
+    moment.updateLocale('zh-cn', newLocale)
+    dayjs.updateLocale('zh-cn', newLocale)
+    dayjs.locale('zh-cn')
+    moment.locale('zh-cn')
+    expect(dayjs().format(formatString))
+      .toEqual('testMonth testFormat')
+
+    expect(dayjs().format(formatString))
+      .toEqual(moment().format(formatString))
+  })
+})
diff --git a/types/plugin/minMax.d.ts b/types/plugin/minMax.d.ts
index 1cca06ef2..f1673500c 100644
--- a/types/plugin/minMax.d.ts
+++ b/types/plugin/minMax.d.ts
@@ -1,4 +1,4 @@
-import { PluginFunc, ConfigType } from 'dayjs'
+import { PluginFunc } from 'dayjs'
 
 declare const plugin: PluginFunc
 export = plugin
diff --git a/types/plugin/updateLocale.d.ts b/types/plugin/updateLocale.d.ts
new file mode 100644
index 000000000..44bce470d
--- /dev/null
+++ b/types/plugin/updateLocale.d.ts
@@ -0,0 +1,8 @@
+import { PluginFunc } from 'dayjs'
+
+declare const plugin: PluginFunc
+export = plugin
+
+declare module 'dayjs' {
+  export function updateLocale(localeName: String, customConfig: Object): any
+}