my member can login without password at Jcow Version 3.0.2. how it can be?

To avoid misunderstanding, you need to tell the details when asking a question.

ok, one of my member, she can login without password, and i don't know, how it can be?

That is because she hasn't picked a password for her account.

ooh, ok, i see :), thank you

Give some validation error, if user not fill there password.