The present invention relates to a method for operating a first communication node in a wireless local area network (WLAN) supporting a multi-link operation, comprising the steps of: setting a first transmit window size of a first link for transmitting a plurality of frames to a second communication node; transmitting the plurality of frames through the first link; when the state of a channel detected through channel sensing in the second link is an idle state, setting a transmit opportunity (TXOP) in the channel; and when the transmit opportunity is set, performing an agreement with the second communication node on the size of a second transmit window for transmitting the plurality of frames. Therefore, it is possible to improve the performance of a communication system.