A method and apparatus of accessing a channel in a wireless local area network is provided. The method includes receiving, by a device, an operation element for setting up or switching at least one channel from an access point (AP), the operation element including a channel type field indicating whether the at least one channel is either a single channel or multiple channels, and the operation element including two channel center frequency segment fields indicating channel center frequency of a primary channel and a secondary channel respectively if the channel type field indicates that the at least one channel is multiple channels, determining whether the primary channel is idle during a first interval, determining whether the secondary channel is idle during a second interval if the primary channel is idle, and transmitting data by using the primary channel and the secondary channel to the AP or at least one station in a basic service set (BSS) if the primary channel and the secondary channel are idle.