The invention discloses a dimension reduction multi-beam antenna system. The system is characterized in that: an N / n-in N-out (e.g., two-in eight-out) feed network is designed between radio frequency ports and an antenna, an antenna system architecture is optimally designed, based on the design, the number of the radio frequency ports can be reduced to 1 / n (e.g., 1 / 4) of an existing scheme, and antenna beam dimension reduction is correspondingly carried out, so that unnecessary channel resource waste is reduced through dimension reduction, and the formed beam direction can meet the predetermined space coverage requirement of the pitching surface. Therefore, the dimension reduction multi-beam antenna system greatly reduces the number of radio frequency links, correspondingly reduces the dimension of matrix operation in rear-end signal processing, and reduces the calculation power consumption. In addition, the power input state of each group of beams can be independently adjusted in real time according to user distribution, and the power expenses in a few-user or no-user scene within the coverage range of a certain beam cluster can be correspondingly reduced.