Hi Qingrou
There is a setting in the Upload users 'Create password if needed and send via email'
The text of the message sent is in the language pack with the string newusernewpasswordtext and is customisable.
The standard text is below this includes the new password and instructions for changing this.
Hi {$a->firstname}, A new account has been created for you at '{$a->sitename}' and you have been issued with a new temporary password. Your current login information is now: username: {$a->username} password: {$a->newpassword} (you will have to change your password when you login for the first time) To start using '{$a->sitename}', login at {$a->link} In most mail programs, this should appear as a blue link which you can just click on. If that doesn't work, then cut and paste the address into the address line at the top of your web browser window. Cheers from the '{$a->sitename}' administrator, {$a->signoff}
Regards