The invention provides an MBR (membrane bioreactor) system with low energy consumption and high treatment capability. The MBR system comprises a sealed MBR, a water inlet pipeline, a water outlet pipeline, a gas inlet pipeline and an exhaust pipeline, wherein the MBR comprises a biochemical assembly and a membrane assembly; air or oxygen is introduced into the MBR through the gas inlet pipeline for aeration, and certain pressure is formed in the MBR. The MBR system has the advantages that 1, a pressure aeration technology is used, so that the dissolved oxygen concentration of an aerobic pool in the biochemical treatment assembly is greatly improved; 2, high aeration intensity can be realized through small aeration quantity, so that the aeration pool volume can be greatly reduced; further, the volume and the cost of the MBR system are reduced; 3, the gas pressure driving is used for replacing the existing self sucking pump driving mode for reducing the membrane driving energy consumption; 4, the gas circulation of an aeration system is realized in various modes, so that the gas overbottom pressure is fully utilized, and the energy consumption of the system is further reduced.