Here we go lads. It's time for me to help our community.

I put some screen shots, but even in case of a dead URL I tried to explain it clearly so you do not really need it.

1/ Log-in via https://www.battlenet.com.cn/v

2/ Then you arrive in your account management desktop. Here you are able to see all your game accounts. Mine is empty because I made a new one for this "How to".
Below your adress mail (which is your account name), there is three choice. Click on this one: 修改密码 (Change your password) which is actually the first one.



3/ Usual way:

- Old password
- New password
- New password again.

Battlenet requirements concerning the password :

- Your password may have, letter (A-Z), number (O,9) and symbol (!$%).
- Your password must contain at least one letter.
- Password length, 8-16 characters.
- For your safety, we recommend you to choose an unique password.



4/ Congratulations you did it.