How to get user registered email and detail?

you will need to use SQL to do this. This query

select author_name, author_email from mt_author;

will produce a list of names and email addresses, you should be able to save the results as a csv file or similar in whatever program you use to manage your database.

I'd recommend phpMyAdmin.

In phpMyAdmin, you'd do this:

1) Run select authorname, authoremail from mt_author; 2) Scroll down to "export" at the bottom of the results page. 3) Export it as a CSV file.

Thanks for the reply,

anyway, where can i find phpMyAdmin? is it built in with MT?

No, it's usually provided by your host.