现有的答案忽略了第二步，并且有过多的细节。

切换一个现有的子模块来跟踪一个新的远程url和/或一个新的分支:

在.gitmodules中编辑真相的来源。

例如，从

[submodule "api"]
    path = api
    url = https://github.com/<original_repo>/api.git

to

[submodule "api"]
    path = api
    url = https://github.com/<another_repo>/api.git
    branch = work-in-progress

你也可以使用hexsha来进行提交哈希。或标签，但见3。

git子模块同步:从.gitmodules中指定的刚刚编辑过的真值源中更新git在.git/modules中缓存的子模块的描述。 只有当你指定一个标签:git submodule foreach——recursive 'git fetch——tags'来获取标签。 git子模块update——init——recursive——remote:更新工作副本中签出的子模块。 提交更改。

使用下面的命令

添加子模块(分支-分支)

git submodule add -b stage git@github.optum.com:orgname/${reponame}.git

更新子模块(分支-分支)

######Clone########

> git clone -b master --single-branch --recurse-submodules git@github.com:orgname/project.git  
or  
> git clone -b stage --single-branch --recurse-submodules git@github.com:orgname/project.git

######Update#######
> git submodule update  --remote (only for remote branch -ie master) 
or 
> git submodule update --recursive --remote

> git submodule update --init --recursive (for remaining branchs)

if you get fatal need single revision error then use below commands:-

before:-

*** stage
  remotes/origin/stage**

git branch -a

git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/{branch name}
ex:- git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/stage

after:-
*** stage
  remotes/origin/HEAD -> origin/stage
  remotes/origin/stage**

then 

> git reset --hard

#hard reset revisions#

> git submodule foreach git reset --hard origin/develop

> git submodule foreach git pull origin develop

在提交和推送相应的.. 现在子模块将得到更新。

根据我的经验，在超级项目或未来的签出中切换分支仍然会导致子模块的头部分离，无论子模块是否正确添加和跟踪(即@djacobs7和@Johnny Z答案)。

而不是手动签出正确的分支手动或通过脚本git子模块foreach可以使用。

这将检查子模块配置文件中的分支属性并检出set分支。

Git子模块foreach -q——recursive 'branch="$(Git config -f $ topllevel . "gitmodules子模块。name.branch美元)”;Git checkout $branch'

Git子模块add -b develop——name branch-name——https://branch.git

我想在这里补充一个答案，它实际上只是其他答案的综合，但我认为它可能更完整。

有了这两个东西，就有了Git子模块。

Your .gitmodules has an entry like so: [submodule "SubmoduleTestRepo"] path = SubmoduleTestRepo url = https://github.com/jzaccone/SubmoduleTestRepo.git You have a submodule object (named SubmoduleTestRepo in this example) in your Git repository. GitHub shows these as "submodule" objects. Or do git submodule status from a command line. Git submodule objects are special kinds of Git objects, and they hold the SHA information for a specific commit. Whenever you do a git submodule update, it will populate your submodule with content from the commit. It knows where to find the commit because of the information in the .gitmodules. Now, all the -b does is add one line in your .gitmodules file. So following the same example, it would look like this: [submodule "SubmoduleTestRepo"] path = SubmoduleTestRepo url = https://github.com/jzaccone/SubmoduleTestRepo.git branch = master Note: only branch name is supported in a .gitmodules file, but SHA and TAG are not supported! (instead of that, the branch's commit of each module can be tracked and updated using "git add .", for example like git add ./SubmoduleTestRepo, and you do not need to change the .gitmodules file each time) The submodule object is still pointing at a specific commit. The only thing that the -b option buys you is the ability to add a --remote flag to your update as per Vogella's answer: git submodule update --remote Instead of populating the content of the submodule to the commit pointed to by the submodule, it replaces that commit with the latest commit on the master branch, THEN it populates the submodule with that commit. This can be done in two steps by djacobs7 answer. Since you have now updated the commit the submodule object is pointing to, you have to commit the changed submodule object into your Git repository. git submodule add -b is not some magically way to keep everything up to date with a branch. It is simply adds information about a branch in the .gitmodules file and gives you the option to update the submodule object to the latest commit of a specified branch before populating it.

Git 1.8.2增加了跟踪分支的可能性。

# add submodule to track branch_name branch
git submodule add -b branch_name URL_to_Git_repo optional_directory_rename

# update your submodule
git submodule update --remote 

参见Git子模块