The embodiment of the invention provides a multicast data packet transmission method and a multicast data packet transmission device, relates to the field of communication, and specifies how to send multicast data to a STA by way of multicast AID. The method comprises the following steps: an access point AP assigns a corresponding multicast association identifier AID to a station STA, wherein the multicast AID is set in a short media access control MAC frame head of a multicast data packet, and the identifier position of the multicast AID is provided with a first identifier; and the AP sends the multicast data packet to at least two STAs to enable the at least two STAs to judge whether the multicast data packet is a multicast data packet corresponding to the at least two STAs according to the multicast AID, wherein the at least two STAs are located in the same multicast group.