A method for uplink multiuser data transmission and a system for uplink multiuser multiple input multiple output are provided. The method includes: sending, by an access point (AP), indication information to at least two stations (STAs), wherein the indication information is used for indicating that the at least two STAs perform an uplink multiuser data transmission; receiving, by the AP, uplink data sent by the at least two STAs through channels from the at least two STAs to the AP, respectively; and demodulating, by the AP, the uplink data sent by the at least two STAs using receiving beams corresponding to pre-estimated channels from the at least two STAs to the AP, respectively.