The present document provides a method for avoiding downlink data collision, an Access Point (AP) and a Station (STA). The method for avoiding downlink data collision includes: an AP receiving a radio frame for inquiring whether the AP has a Bufferable Unit (BU) of an STA transmitted by the STA; and after determining that there is a BU of the STA and the BU is larger than a predetermined threshold, the AP exchanging radio frames with the STA to reserve a channel, and transmitting the BU to the STA after succeeding in reserving the channel. The method can guarantee the fairness among various STAs and the reasonable utilization of channel resources, thus avoiding the collision; furthermore, the channel reservation frame transmitted by the AP can reserve a longer period of time, i.e. a plurality of BUs can be transmitted to the STA at a time, thus saving the link overhead.