The present invention discloses an FDD (Frequency Division Duplex) system based multi-user beamforming method and device. In the method, when two or more user terminals are at respective AOAs (Angles of Arrival), a transmit weight of a downlink signal of each user terminal is determined by using a null-widening algorithm, and the transmit weight is stored in a network side, the network side groups the user terminals based on AOA information reported by the user terminals, a corresponding transmit weight for the downlink signal of each user terminal in each group is selected based on the AOA information of the user terminals in the group, and the selected transmit weight is transmitted after multiplying it by a downlink data stream of the user terminal corresponding to the transmit weight.