Abstract: The present invention belongs to the technical field of wireless communication, and particularly relates to a method for grouping users based on out-of-band spatial information in a multi-user millimeter wave system. By a grouping strategy, the out-of-band spatial information is fully utilized and the search range is narrowed on the base station side to perform beam search within a more accurate initial range. On the user side, the number of receiving beam search times is reduced and the energy consumption is saved for users by a strategy that search subframes which are not in the group keep mute. In the feedback process, the user side just needs to feed back beam matching information within search subframes corresponding to the group. The disadvantage that more redundant information is fed back in a traditional search method is overcome, so the feedback overhead is reduced and the system efficiency is improved.