A method and an apparatus for accessing heterogeneous networks via a Wireless Local Area Network (WLAN) are disclosed. The method includes receiving an access request from a WLAN terminal or a portal/policy server; determining a target network that the terminal needs to access according to the access request; converting the access request according to the format of a target network transmission protocol; sending the converted access request to the target network; and receiving an authentication result from the target network, and sending the authentication result to the terminal.