This application provides a data transmission method. When performing data transmission with a first station in a bandwidth power saving mode by using an operating channel of the first station, an access point performs data transmission with a second station by using an operating channel of the second station. Therefore, even if the operating channel of the first station includes a primary channel, the access point can still perform data transmission with the second station by using another channel. Further, for the access point, although the operating channel of the first station occupies only a part of available bandwidth resources of the access point, the access point can still perform data transmission with the second station by using a remaining channel. In this way, all bandwidth resources of the access point except for the operating channel of the first station can also be used for data transmission at the same time, improving resource utilization of the access point.