Embodiments of the present invention provide an association establishment method and apparatus. The method includes: broadcasting, by an access point AP, a trigger frame, wherein the trigger frame is used to trigger one or more unassociated stations STAs to perform uplink data transmission and indicate one or more available subchannels for random accessing of the unassociated STAs; receiving, by the AP, one or more association request messages sent on available subchannels acquired by the unassociated STAs; broadcasting, by the AP, a multi-block acknowledgement M-BA frame, wherein the M-BA frame includes one or more pieces of association acknowledgement information and the association acknowledgement information is acknowledgement information of the association request message. In this way, the AP is associated with the unassociated stations STA, and communication reliability is ensured.