The present invention provides a data transmission method, where the method is executed by a base station in a communications system, the communications system further includes a wireless local area network access point WLAN AP and user equipment, a bearer used to transmit data of the user equipment is disposed between the base station and a gateway device, a General Packet Radio Service Tunneling Protocol GTP tunnel is disposed between the base station and the WLAN AP, and the method includes: sending, by the base station, first offloading indication information to the WLAN AP, where the first offloading indication information is used for instructing the WLAN AP to transmit the target data between the base station and the user equipment, and the first offloading indication information includes identity information of the user equipment.