A method includes: A multi-link device performs first channel contention on a first link, where an initial value of a backoff counter in the first channel contention is determined based on a first value of a contention window. The multi-link device may perform second channel contention on the first link when a value of the backoff counter becomes 0 in the first channel contention and the multi-link device does not perform transmission on the first link, where an initial value of the backoff counter in the second channel contention is determined based on a second value of the contention window, and the second value is equal to the first value or a minimum value of the contention window.