The reverse osmosis device is an equipment to purify the saline water with the action of pressure difference of semi-permeable membrane. It is called reverse osmosis, as it is counter to natural penetration direction. Different material has different osmotic pressures. The reverse osmosis method to adopt large osmotic pressures is used to obtain the purpose to separate, extract, purify and 99% gules, microbe, particulate and organic substances and etc. can be removed with the reverse osmosis. It becomes the most ideal equipment for the modern program of pure water, hyper pure water, and airspace water. The remarkable characteristics of the equipment are shown as lower energy consumption, no pollution, high water quality, easy to operation and maintenance.