A channel listening method applied to an unlicensed frequency band, and an apparatus are provided, where the method includes: performing, by a communications device, clear channel assessment on a first beam, and in a process of the clear channel assessment, performing, by the communications device, a backoff based on a backoff control parameter for the first beam, where the communications device has a plurality of optional beams, the first beam is one of the plurality of optional beams, and the backoff control parameter is set based on a historical value of a backoff control parameter for at least one of the plurality of optional beams; and after the backoff succeeds, performing, by the communications device, transmission by using the first beam.