The invention discloses a method and system for enabling a terminal to access into a network, relates to the technical field of communications, and solves the problem of loss of network business due to a network failure easily caused in an upgrading and reconstruction process of existing network equipment. The method comprises the following steps: when receiving an access request sent by a double-stack terminal, a single-stack BNG (Broadband Network Gateway) acquires a double-stack access strategy corresponding to the double-stack terminal from a double-stack AAA (Authentication Authorization Accounting) server; the single-stack BNG acquires address information of the double-stack terminal from a double-stack vBNG (virtual Broadband Network Gateway) through a VxLAN (Virtual extensible Local Area Network) tunnel according to the double-stack access strategy; the single-stack BNG sends the address information to the double-stack terminal; and when receiving a network access request sent by the double-stack terminal, the single-stack BNG sends the network access request to the double-stack vBNG through the VxLAN tunnel, so that the double-stack vBNG can conveniently send the network access request to a backbone network through a double-stack CR (Core Router). The method and the system are applicable to a process of enabling the double-stack terminal to access the network.