A dual band communication method and a wireless local area network (WLAN) device, First determining a service type of a service in a switching period according to a preset policy, where the switching period includes one first timeslot in which a first radio frequency (RF) channel works and one adjacent second timeslot in which a second RF channel works, and determining, according to the determined service type and a preset service quality requirement corresponding to the service type, maximum duration of the switching period in which the service quality requirement is met, and when time division multiplexing (TDM) is performed on a baseband processor, controlling the switching between the first RF channel and the second RF channel according to the maximum duration, hence actual duration of the switching period is less than or equal to the maximum duration.