Embodiments of the present invention relate to communication technologies, in particular, to a method and an apparatus for protocol transmission in a wireless local area network. A method for transmitting multi-user data in a reverse direction protocol according to an embodiment of the present invention includes: within a transmission opportunity (TXOP) of a first station, if the TXOP is not over after the first station finishes sending data to an access point (AP), obtaining, by the AP, the TXOP, where the obtaining, by the AP, the TXOP is implemented through granting a remaining part of the TXOP to the access point AP by the first station as a reverse direction protocol initiator; and within the TXOP, sending, by the AP, second data to at least two stations, where the at least two stations include the first station.