https://support.google.com/a/answer/100458?hl=en

The official method is not good, we will lose (Google Document) format information.

Recently I find a way to migrate my documents from my Google Apps account chenyang[at]masols.com to my personal account, say chenyang[at]gmail.com

  1. In chenyang[at]masols.com
    • At ROOT dir, create a folder _shared_to_accounts_out_of_this_domain_, and shared with chenyang[at]gmail.com.
    • Then move all files and folders to this folder.
  2. In chenyang[at]gmail.com
    • At ROOT dir, create a folder _working_tmp_dir_
    • Open “Shared with me” in sidebar.
    • Find folder _shared_to_accounts_out_of_this_domain_, right click on it, select “Move to…”, and then choose the _working_tmp_dir_.
    • At the time, we got all files/dirs in ROOT/_working_tmp_dir_/_shared_to_accounts_out_of_this_domain_/*
  3. Install Google Drive (for Windows)
    • Login with chenyang[at]gmail.com
    • Only sync ROOT/_working_tmp_dir_ to local machine.
    • After all files/dirs are synced to local, copy ROOT/_working_tmp_dir_/_shared_to_accounts_out_of_this_domain_ to ROOT/_working_tmp_dir_/_copy_files_
    • Wait for all things are synced to remote.
  4. In chenyang[at]masols.com
    • Stop sharing to chenyang[at]gmail.com at step 1

At last, you will find all the files/dirs at ROOT/_working_tmp_dir_/_copy_files_, and you can do anything you want.