Disclosed are a method and apparatus for multi-channel operation, performed by an access point (AP), in a WLAN system, the method includes: transmitting channel assignment information to a plurality of stations (STAs), in which the channel assignment information is for assigning at least one of a first channel and a second channel to each of the plurality of STAs; transmitting channel activity information to the plurality of STAs, in which the channel activity information is for indicating an activity duration where the AP transmit or receive a frame through each of the first channel and the second channel; and transmitting or receiving a frame through the first channel or the second channel on the basis of the channel activity information.