An adaptive multi-antenna data transmission method, apparatus, and system are provided. The adaptive multi-antenna data transmission method includes: acquiring, at a current time interval, a beam adjustment parameter of user equipment UE; adjusting a beam width of the UE according to the beam adjustment parameter of the UE; and performing precoding processing on to-be-transmitted data of the UE according to an adjusted beam width of the UE and direction information of the UE, so as to perform data transmission. A beam width of UE is adjusted, so that a direction of a beam during data transmission can better match a direction of the UE. Therefore, a status or quality of a link for the UE is improved and a performance loss is reduced.