Usually by the raw water pretreatment system, reverse osmosis purification system, ultra-purification post-treatment system consists of three parts. The purpose of pretreatment is mainly to make the raw water to reach the reverse osmosis membrane separation components of the water requirements, to ensure the stable operation of the reverse osmosis purification system. Reverse osmosis membrane system is a one-time removal of raw water more than 98% of ions, organic matter and 100% of microorganisms (theoretically) the most cost-effective purification method. Ultra-purification post-treatment system through a variety of integrated technology to further remove reverse osmosis purified water in the remaining trace ions, organics and other impurities, in order to meet the requirements of the final water quality indicators for different purposes.