A data transmission method including sending, by a base station, request information, an identifier of a wireless local area network (WLAN) access point (AP), and a first Internet Protocol (IP) address of the base station to user equipment, receiving, by the base station, a second IP address assigned by the WLAN AP to the user equipment and confirmation information that are sent by the user equipment, and performing, by the base station, multi-stream aggregation data transmission to the user equipment using the WLAN AP and through the IP tunnel, where the IP tunnel is determined using the first IP address and the second IP address.