diff --git a/autoload/SpaceVim/layers/git.vim b/autoload/SpaceVim/layers/git.vim
index ec67ff5a6..5f0382a21 100644
--- a/autoload/SpaceVim/layers/git.vim
+++ b/autoload/SpaceVim/layers/git.vim
@@ -47,6 +47,11 @@
 "   SPC g h r     undo cursor hunk
 "   SPC g h v     preview cursor hunk
 " <
+" @subsection commit omni function
+" This layer also provides an omnifunc for git commit messages. It supports:
+" 1. complete commit title, `fix:`, `doc:` etc.
+" 2. complete github issue list
+" 3. complete co-author info
 
 
 if exists('s:git_plugin')
diff --git a/autoload/SpaceVim/plugins/gitcommit.vim b/autoload/SpaceVim/plugins/gitcommit.vim
index 788360d61..4f3e6ec6c 100644
--- a/autoload/SpaceVim/plugins/gitcommit.vim
+++ b/autoload/SpaceVim/plugins/gitcommit.vim
@@ -6,6 +6,7 @@
 " License: GPLv3
 "=============================================================================
 
+let s:list = SpaceVim#api#import('data#list')
 
 let s:pr_kind = g:spacevim_gitcommit_pr_icon
 let s:issue_kind = g:spacevim_gitcommit_issue_icon
@@ -62,19 +63,56 @@ let s:commit_types = [
       \ ]
 
 
+" https://docs.github.com/en/pull-requests/committing-changes-to-your-project/creating-and-editing-commits/creating-a-commit-with-multiple-authors
+" https://stackoverflow.com/questions/58525836/git-magic-keywords-in-commit-messages-signed-off-by-co-authored-by-fixes
+" https://www.reddit.com/r/git/comments/13d565i/git_trailers_what_are_they_for/
+" https://alchemists.io/articles/git_trailers
+" https://git-scm.com/docs/git-interpret-trailers
+" https://gitlab.com/gitlab-org/gitlab-foss/-/issues/31640
+" https://archive.kernel.org/oldwiki/git.wiki.kernel.org/index.php/CommitMessageConventions.html
+let s:git_trailers = [
+      \ {
+      \   'word' : 'Co-Authored-By:',
+      \   'menu' : 'multiple commit author'
+      \ },
+      \ ]
+
+function! s:find_last_branch() abort
+  let reflog = systemlist('git reflog')
+  for log in reflog
+    " e059b76ca HEAD@{15}: checkout: moving from doc-help to master
+    if log =~# 'HEAD@{\d\+}: checkout: '
+      return matchstr(log, 'HEAD@{\d\+}: checkout: moving from \zs\S*')
+    endif
+  endfor
+  return ''
+endfunction
+
+function! s:generate_co_author() abort
+  let last_branch = s:find_last_branch()
+  call SpaceVim#logger#info('last branch:' . last_branch)
+  return s:list.uniq(systemlist('git log -n 5 --format="%aN <%aE>" ' . last_branch))
+endfunction
+
 function! SpaceVim#plugins#gitcommit#complete(findstart, base) abort
   if a:findstart
     let s:complete_ol = 0
     let s:complete_type = 0
+    let s:complete_trailers = 0
+    let s:complete_co_author = 0
     let line = getline('.')
     let start = col('.') - 1
-    while start > 0 && line[start - 1] !=# ' ' && line[start - 1] !=# '#'
+    while start > 0 && line[start - 1] !=# ' ' && line[start - 1] !=# '#' && line[start - 1] !=# ':'
       let start -= 1
     endwhile
     if line[start - 1] ==# '#'
       let s:complete_ol = 1
     elseif line('.') ==# 1 && start ==# 0
       let s:complete_type = 1
+    elseif line('.') !=# 1 && start ==# 0
+      let s:complete_trailers = 1
+    elseif getline('.') =~# '^Co-Authored-By:' && start >= 14
+      let s:complete_co_author = 1
     endif
     return start
   else
@@ -82,6 +120,10 @@ function! SpaceVim#plugins#gitcommit#complete(findstart, base) abort
       return s:complete_pr(a:base)
     elseif s:complete_type == 1
       return s:complete('types')
+    elseif s:complete_trailers == 1
+      return s:complete('trailers')
+    elseif s:complete_co_author == 1
+      return s:complete('co-author')
     endif
     let res = []
     for m in s:cache_commits()
@@ -101,6 +143,10 @@ endfunction
 function! s:complete(what) abort
   if a:what ==# 'types'
     return s:commit_types
+  elseif a:what ==# 'trailers'
+    return s:git_trailers
+  elseif a:what ==# 'co-author'
+    return s:generate_co_author()
   else
     return []
   endif
diff --git a/doc/SpaceVim.txt b/doc/SpaceVim.txt
index ed548b54d..d63050385 100644
--- a/doc/SpaceVim.txt
+++ b/doc/SpaceVim.txt
@@ -2423,6 +2423,11 @@ The following key bindings will be definded when the `git` layer is loaded.
   SPC g h r     undo cursor hunk
   SPC g h v     preview cursor hunk
 <
+COMMIT OMNI FUNCTION
+This layer also provides an omnifunc for git commit messages. It supports:
+  1. complete commit title, `fix:`, `doc:` etc.
+  2. complete github issue list
+  3. complete co-author info
 
 ==============================================================================
 GITHUB                                                *SpaceVim-layers-github*
diff --git a/docs/cn/layers/git.md b/docs/cn/layers/git.md
index 43f207026..451e8b1e8 100644
--- a/docs/cn/layers/git.md
+++ b/docs/cn/layers/git.md
@@ -12,6 +12,7 @@ lang: zh
 - [启用模块](#启用模块)
 - [模块选项](#模块选项)
 - [快捷键](#快捷键)
+- [Commit message 补全](#commit-message-补全)
 
 <!-- vim-markdown-toc -->
 
@@ -57,3 +58,11 @@ lang: zh
 | `SPC g h a` | stage current hunk   |
 | `SPC g h r` | undo cursor hunk     |
 | `SPC g h v` | preview cursor hunk  |
+
+## Commit message 补全
+
+在编辑 git commit message 时，可以使用快捷键 `ctrl-x_ctrl-o` 进行补全，可以补全：
+
+1. 标题前缀, 如 `fix:`、`doc:` 等；
+2. GitHub issue 列表；
+3. 上一次使用分支的 author 信息，便于添加 co-author
diff --git a/docs/layers/git.md b/docs/layers/git.md
index f69c39f40..2ab116b37 100644
--- a/docs/layers/git.md
+++ b/docs/layers/git.md
@@ -11,6 +11,7 @@ description: "This layer adds extensive support for git"
 - [Install](#install)
 - [Layer options](#layer-options)
 - [Key bindings](#key-bindings)
+- [Omnifunc of commit message](#omnifunc-of-commit-message)
 
 <!-- vim-markdown-toc -->
 
@@ -56,3 +57,11 @@ if you want to use `fugitive` instead:
 | `SPC g h a` | stage current hunk     |
 | `SPC g h r` | undo cursor hunk       |
 | `SPC g h v` | preview cursor hunk    |
+
+## Omnifunc of commit message
+
+This layer also provides omnifunc of commit message. The key binding is `ctrl-x_ctrl-o` in insert mode.
+
+1. complete commit title prefix, `fix:`, `doc:` etc.
+2. complete github issue list
+3. complete co-author info