diff --git a/lib/config/default.js b/lib/config/default.js
index 95ee1940..08a4413d 100644
--- a/lib/config/default.js
+++ b/lib/config/default.js
@@ -188,5 +188,6 @@ module.exports = {
   //    2nd appearance: "31-good-morning-my-friend---do-you-have-5-1"
   //    3rd appearance: "31-good-morning-my-friend---do-you-have-5-2"
   linkifyHeaderStyle: 'keep-case',
-  autoVersionCheck: true
+  autoVersionCheck: true,
+  defaultTocDepth: 3
 }
diff --git a/lib/config/environment.js b/lib/config/environment.js
index 0867aecf..cbf0f4c1 100644
--- a/lib/config/environment.js
+++ b/lib/config/environment.js
@@ -147,5 +147,6 @@ module.exports = {
   openID: toBooleanConfig(process.env.CMD_OPENID),
   defaultUseHardbreak: toBooleanConfig(process.env.CMD_DEFAULT_USE_HARD_BREAK),
   linkifyHeaderStyle: process.env.CMD_LINKIFY_HEADER_STYLE,
-  autoVersionCheck: toBooleanConfig(process.env.CMD_AUTO_VERSION_CHECK)
+  autoVersionCheck: toBooleanConfig(process.env.CMD_AUTO_VERSION_CHECK),
+  defaultTocDepth: toIntegerConfig(process.env.CMD_DEFAULT_TOC_DEPTH)
 }
diff --git a/lib/status/index.js b/lib/status/index.js
index 2f5366d6..2e344efa 100644
--- a/lib/status/index.js
+++ b/lib/status/index.js
@@ -41,7 +41,8 @@ exports.getConfig = (req, res) => {
     allowedUploadMimeTypes: config.allowedUploadMimeTypes,
     defaultUseHardbreak: config.defaultUseHardbreak,
     linkifyHeaderStyle: config.linkifyHeaderStyle,
-    useCDN: config.useCDN
+    useCDN: config.useCDN,
+    defaultTocDepth: config.defaultTocDepth
   }
   res.set({
     'Cache-Control': 'private', // only cache by client
diff --git a/public/js/extra.js b/public/js/extra.js
index b203280e..9adab000 100644
--- a/public/js/extra.js
+++ b/public/js/extra.js
@@ -813,7 +813,7 @@ export function generateToc (id) {
   /* eslint-disable no-unused-vars */
 
   var tocOptions = md.meta.toc || {}
-  var maxLevel = (typeof tocOptions.maxLevel === 'number' && tocOptions.maxLevel > 0) ? tocOptions.maxLevel : 3
+  var maxLevel = (typeof tocOptions.maxLevel === 'number' && tocOptions.maxLevel > 0) ? tocOptions.maxLevel : window.defaultTocDepth
 
   var toc = new window.Toc('doc', {
     level: maxLevel,
@@ -1016,7 +1016,7 @@ export function renderTOC (view) {
     /* eslint-disable no-unused-vars */
 
     var tocOptions = md.meta.toc || {}
-    var maxLevel = (typeof tocOptions.maxLevel === 'number' && tocOptions.maxLevel > 0) ? tocOptions.maxLevel : 3
+    var maxLevel = (typeof tocOptions.maxLevel === 'number' && tocOptions.maxLevel > 0) ? tocOptions.maxLevel : window.defaultTocDepth
 
     const TOC = new window.Toc('doc', {
       level: maxLevel,
diff --git a/public/js/lib/common/constant.ejs b/public/js/lib/common/constant.ejs
index 57438912..3cb960ff 100644
--- a/public/js/lib/common/constant.ejs
+++ b/public/js/lib/common/constant.ejs
@@ -13,3 +13,5 @@ window.linkifyHeaderStyle = '<%- linkifyHeaderStyle %>'
 window.DROPBOX_APP_KEY = '<%- DROPBOX_APP_KEY %>'
 
 window.USE_CDN = <%- useCDN %>
+
+window.defaultTocDepth = <%- defaultTocDepth %>