The invention discloses a novel membrane concentration system which comprises a pretreatment device, a reverse osmosis device, a high-power concentration device, an ion exchange device and an advanced oxidation device, wherein high-multiple concentration can be realized; besides, the operation pressure is low, and the operation energy consumption of the system is greatly reduced. According to the novel membrane concentration process, the characteristics of reverse osmosis membranes are fully utilized, and part of concentrated water of a next-stage weak reverse osmosis membrane flows back to the water production side of a previous-stage weak reverse osmosis membrane, so that the inorganic salt content of the water production side of the previous-stage weak reverse osmosis membrane is increased, and the osmotic pressure difference between the concentrated water side and the water production side of the weak reverse osmosis membrane is reduced; furthermore, high-multiple concentration is realized under relatively low operation pressure. The invention further discloses a high-power concentration device, and the content of inorganic salt in concentrated water is gradually increased through a multi-stage weak reverse osmosis membrane; wherein, a backflow water inlet is formed in the water production side of each previous-stage weak reverse osmosis membrane, so that part of concentrated water flows back, and finally, high-multiple concentration is realized.