Data transmitting method and relevant device and system

The embodiment of the invention discloses a data transmitting method, which includes the following steps: an access point receives a user side data sent by a terminal; the type of the user side data is detected; if the user side data is detected to be data which accesses a local network, the data which accesses the local network carries out network address conversion and is transmitted to the local network; and if the user side data is detected to be data which accesses the Internet, the data for accessing the Internet is transmitted to a wireless network controller proxy in an access gateway, so as to lead the data for accessing the Internet to be transmitted from a gateway support node in the access gateway to the Internet. The embodiment of the invention further provides a relevant device and a system. The embodiment of the invention can improve the user's experience by the way that a terminal internet service can not be interrupted when the terminal for Internet service is switched to an access point community from a macro network.