The invention discloses a broadband access method, terminal, server and system for performing secondary authentication. The broadband access method for performing the secondary authentication comprises the steps: an authentication server performs first authentication according to preset account and passwords of a terminal; if the first authentication succeeds, configuration information is transmitted to a broadband remote access server (BRAS), at which the terminal is located; the BRAS allocates an IP address to the terminal and transmits the configuration information, and the terminal accesses a network; broadband line information of the terminal matches real account and passwords of a user, and the real account and passwords are encrypted by keys and then are transmitted to the terminal, and secondary authentication is performed; the terminal re-dials according to the real account and passwords, and after an authentication server passes the secondary authentication, normal broadband access is performed. According to the broadband access method, terminal, server and system for performing the secondary authentication, the original mode of configuring broadband account and passwords by the user is changed to be a mode of automatic configuration on a network side; therefore, configuration operations are simplified, and the security is improved.