From：http://jasonkarns.com/blog/subdirectory-checkouts-with-git-sparse-checkout/

If there is one thing I miss about SVN having switched to git (and trust me, it’s the only thing), it is the ability to checkout only a sub-tree of a repository. As of version 1.7, you can check out just a sub-tree in git as well! Now not only does git support checking out sub-directories, it does it better than subversion!

New Repository

There is a bit of a catch-22 when doing a sub-tree checkout for a new repository. In order to only checkout a sub-tree, you’ll need to have the core.sparsecheckout option set to true. Of course, you need to have a git repository before you can enable sparse-checkout. So, rather than doing a git clone, you’ll need to start with git init.

1. Create and initialize your new repository:

   mkdir <repo> && cd <repo>
   
   git init
   
   git remote add –f <name> <url>

2. Enable sparse-checkout:

   git config core.sparsecheckout true

3. Configure sparse-checkout by listing your desired sub-trees in .git/info/sparse-checkout:

   echo some/dir/ >> .git/info/sparse-checkout
   
   echo another/sub/tree >> .git/info/sparse-checkout

4. Checkout from the remote:

   git pull <remote> <branch>

Existing Repository

If you already have a repository, simply enable and configure sparse-checkout as above and do git read-tree.

1. Enable sparse-checkout:

   git config core.sparsecheckout true

2. Configure sparse-checkout by listing your desired sub-trees in .git/info/sparse-checkout:

   echo some/dir/ >> .git/info/sparse-checkout
   
   echo another/sub/tree >> .git/info/sparse-checkout

3. Update your working tree:

   git read-tree -mu HEAD

Modifying sparse-checkout sub-trees

If you later decide to change which directories you would like checked out, simply edit the sparse-checkout file and run git read-tree again as above.

Be sure to read the documentation on read-tree/sparse-checkout. The sparse-tree file accepts file patterns similar to .gitignore. It also accepts negations—enabling you to specify certain directories or files to not checkout.

Now there isn’t anything that svn does better than git!