diff --git a/doc/KEYBINDINGS.md b/doc/KEYBINDINGS.md
index e346f22b..628f1be7 100644
--- a/doc/KEYBINDINGS.md
+++ b/doc/KEYBINDINGS.md
@@ -89,6 +89,7 @@ Here is an example:
 | ------------------- | ------------------------------------------- |
 | `formatStrong`      | Set the font of the selected text to bold   |
 | `formatEmphasis`    | Set the font of the selected text to italic |
+| `formatUnderline`   | Change the selected text to underline       |
 | `formatInlineCode`  | Change the selected text to inline code     |
 | `formatStrike`      | Strike through the selected text            |
 | `formatHyperlink`   | Insert a hyperlink                          |
diff --git a/src/main/menus/format.js b/src/main/menus/format.js
index aca5664b..e1c9b6c0 100644
--- a/src/main/menus/format.js
+++ b/src/main/menus/format.js
@@ -20,6 +20,32 @@ export default {
     click (menuItem, browserWindow) {
       actions.format(browserWindow, 'em')
     }
+  }, {
+    id: 'underlineMenuItem',
+    label: 'Underline',
+    type: 'checkbox',
+    accelerator: keybindings.getAccelerator('formatUnderline'),
+    click (menuItem, browserWindow) {
+      actions.format(browserWindow, 'u')
+    }
+  }, {
+    type: 'separator'
+  }, {
+    id: 'superscriptMenuItem',
+    label: 'Superscript',
+    type: 'checkbox',
+    click (menuItem, browserWindow) {
+      actions.format(browserWindow, 'sup')
+    }
+  }, {
+    id: 'subscriptMenuItem',
+    label: 'Subscript',
+    type: 'checkbox',
+    click (menuItem, browserWindow) {
+      actions.format(browserWindow, 'sub')
+    }
+  }, {
+    type: 'separator'
   }, {
     id: 'inlineCodeMenuItem',
     label: 'Inline Code',
diff --git a/src/main/shortcutHandler.js b/src/main/shortcutHandler.js
index abd57883..5a077f8b 100644
--- a/src/main/shortcutHandler.js
+++ b/src/main/shortcutHandler.js
@@ -75,6 +75,7 @@ class Keybindings {
       // format menu
       ['formatStrong', 'CmdOrCtrl+B'],
       ['formatEmphasis', 'CmdOrCtrl+I'],
+      ['formatUnderline', 'CmdOrCtrl+U'],
       ['formatInlineCode', 'CmdOrCtrl+`'],
       ['formatInlineMath', 'Ctrl+M'],
       ['formatStrike', 'CmdOrCtrl+D'],
diff --git a/src/muya/lib/assets/pngicon/format_underline/1.png b/src/muya/lib/assets/pngicon/format_underline/1.png
new file mode 100755
index 00000000..f536e64f
Binary files /dev/null and b/src/muya/lib/assets/pngicon/format_underline/1.png differ
diff --git a/src/muya/lib/assets/pngicon/format_underline/2.png b/src/muya/lib/assets/pngicon/format_underline/2.png
new file mode 100755
index 00000000..fd560fb7
Binary files /dev/null and b/src/muya/lib/assets/pngicon/format_underline/2.png differ
diff --git a/src/muya/lib/assets/pngicon/format_underline/3.png b/src/muya/lib/assets/pngicon/format_underline/3.png
new file mode 100755
index 00000000..c04588be
Binary files /dev/null and b/src/muya/lib/assets/pngicon/format_underline/3.png differ
diff --git a/src/muya/lib/config/index.js b/src/muya/lib/config/index.js
index 4bebbeab..3fb14a53 100644
--- a/src/muya/lib/config/index.js
+++ b/src/muya/lib/config/index.js
@@ -167,7 +167,19 @@ export const FORMAT_MARKER_MAP = {
   'inline_code': '`',
   'strong': '**',
   'del': '~~',
-  'inline_math': '$'
+  'inline_math': '$',
+  'u': {
+    open: '<u>',
+    close: '</u>'
+  },
+  'sub': {
+    open: '<sub>',
+    close: '</sub>'
+  },
+  'sup': {
+    open: '<sup>',
+    close: '</sup>'
+  }
 }
 
 export const FORMAT_TYPES = ['strong', 'em', 'del', 'inline_code', 'link', 'image', 'inline_math']
diff --git a/src/muya/lib/contentState/formatCtrl.js b/src/muya/lib/contentState/formatCtrl.js
index 544fb5fb..acf05c13 100644
--- a/src/muya/lib/contentState/formatCtrl.js
+++ b/src/muya/lib/contentState/formatCtrl.js
@@ -2,7 +2,7 @@ import selection from '../selection'
 import { tokenizer, generator } from '../parser/'
 import { FORMAT_MARKER_MAP, FORMAT_TYPES, URL_REG } from '../config'
 
-const getOffset = (offset, { range: { start, end }, type, anchor, alt }) => {
+const getOffset = (offset, { range: { start, end }, type, tag, anchor, alt }) => {
   const dis = offset - start
   const len = end - start
   switch (type) {
@@ -19,6 +19,16 @@ const getOffset = (offset, { range: { start, end }, type, anchor, alt }) => {
       if (dis > len) return -2 * MARKER_LEN
       break
     }
+    case 'html_tag': { // handle underline, sup, sub
+      const OPEN_MARKER_LEN = FORMAT_MARKER_MAP[tag].open.length
+      const CLOSE_MARKER_LEN = FORMAT_MARKER_MAP[tag].close.length
+      if (dis < 0) return 0
+      if (dis >= 0 && dis < OPEN_MARKER_LEN) return -dis
+      if (dis >= OPEN_MARKER_LEN && dis <= len - CLOSE_MARKER_LEN) return -OPEN_MARKER_LEN
+      if (dis > len - CLOSE_MARKER_LEN && dis <= len) return len - dis - OPEN_MARKER_LEN - CLOSE_MARKER_LEN
+      if (dis > len) return - OPEN_MARKER_LEN - CLOSE_MARKER_LEN
+      break
+    }
     case 'link': {
       const MARKER_LEN = 1
       if (dis < MARKER_LEN) return 0
@@ -50,7 +60,8 @@ const clearFormat = (token, { start, end }) => {
     case 'strong':
     case 'del':
     case 'em':
-    case 'link': {
+    case 'link':
+    case 'html_tag': { // underline, sub, sup
       const { parent } = token
       const index = parent.indexOf(token)
       parent.splice(index, 1, ...token.children)
@@ -90,6 +101,18 @@ const addFormat = (type, block, { start, end }) => {
       end.offset += MARKER.length
       break
     }
+    case 'sub':
+    case 'sup':
+    case 'u': {
+      const MARKER = FORMAT_MARKER_MAP[type]
+      const oldText = block.text
+      block.text = oldText.substring(0, start.offset) +
+        MARKER.open + oldText.substring(start.offset, end.offset) +
+        MARKER.close + oldText.substring(end.offset)
+      start.offset += MARKER.open.length
+      end.offset += MARKER.open.length
+      break
+    }
     case 'link':
     case 'image': {
       const oldText = block.text
@@ -104,6 +127,13 @@ const addFormat = (type, block, { start, end }) => {
   }
 }
 
+const checkTokenIsInlineFormat = token => {
+  const { type, tag } = token
+  if (FORMAT_TYPES.includes(type)) return true
+  if (type === 'html_tag' && /^(?:u|sub|sup)$/i.test(tag)) return true
+  return false
+}
+
 const formatCtrl = ContentState => {
   ContentState.prototype.selectionFormats = function ({ start, end } = selection.getCursorRange()) {
     if (!start || !end) {
@@ -119,14 +149,14 @@ const formatCtrl = ContentState => {
       ;(function iterator (tks) {
         for (const token of tks) {
           if (
-            FORMAT_TYPES.includes(token.type) &&
+            checkTokenIsInlineFormat(token) &&
             start.offset >= token.range.start &&
             end.offset <= token.range.end
           ) {
             formats.push(token)
           }
           if (
-            FORMAT_TYPES.includes(token.type) &&
+            checkTokenIsInlineFormat(token) &&
             ((start.offset >= token.range.start && start.offset <= token.range.end) ||
             (end.offset >= token.range.start && end.offset <= token.range.end) ||
             (start.offset <= token.range.start && token.range.end <= end.offset))
@@ -176,7 +206,10 @@ const formatCtrl = ContentState => {
       }))
     }
 
-    neighbors = type ? neighbors.filter(n => n.type === type) : neighbors
+    neighbors = type ? neighbors.filter(n => {
+      return n.type === type ||
+      n.type === 'html_tag' && n.tag === type
+    }) : neighbors
 
     for (const neighbor of neighbors) {
       clearFormat(neighbor, { start, end })
@@ -263,8 +296,14 @@ const formatCtrl = ContentState => {
     start.delata = end.delata = 0
     if (start.key === end.key) {
       const { formats, tokens, neighbors } = this.selectionFormats()
-      const currentFormats = formats.filter(format => format.type === type).reverse()
-      const currentNeightbors = neighbors.filter(format => format.type === type).reverse()
+      const currentFormats = formats.filter(format => {
+        return format.type === type ||
+          format.type === 'html_tag' && format.tag === type
+      }).reverse()
+      const currentNeightbors = neighbors.filter(format => {
+        return format.type === type ||
+        format.type === 'html_tag' && format.tag === type
+      }).reverse()
       // cache delata
       if (type === 'clear') {
         for (const neighbor of neighbors) {
diff --git a/src/muya/lib/ui/formatPicker/config.js b/src/muya/lib/ui/formatPicker/config.js
index 72876218..79ac3704 100644
--- a/src/muya/lib/ui/formatPicker/config.js
+++ b/src/muya/lib/ui/formatPicker/config.js
@@ -1,5 +1,6 @@
 import strongIcon from '../../assets/pngicon/format_strong/2.png'
 import emphasisIcon from '../../assets/pngicon/format_emphasis/2.png'
+import underlineIcon from '../../assets/pngicon/format_underline/2.png'
 import codeIcon from '../../assets/pngicon/code/2.png'
 import imageIcon from '../../assets/pngicon/format_image/2.png'
 import linkIcon from '../../assets/pngicon/format_link/2.png'
@@ -14,6 +15,9 @@ const icons = [
   }, {
     type: 'em',
     icon: emphasisIcon
+  }, {
+    type: 'u',
+    icon: underlineIcon
   }, {
     type: 'del',
     icon: strikeIcon
diff --git a/src/muya/lib/ui/formatPicker/index.js b/src/muya/lib/ui/formatPicker/index.js
index 3fde9851..05737e6f 100644
--- a/src/muya/lib/ui/formatPicker/index.js
+++ b/src/muya/lib/ui/formatPicker/index.js
@@ -62,7 +62,7 @@ class FormatPicker extends BaseFloat {
       }
       const iconWrapper = h(iconWrapperSelector, icon)
       let itemSelector = `li.item.${i.type}`
-      if (formats.some(f => f.type === i.type)) {
+      if (formats.some(f => f.type === i.type || f.type === 'html_tag' && f.tag === i.type)) {
         itemSelector += '.active'
       }
       return h(itemSelector, {