Nanofiltration technology is a new separation technology between ultrafiltration and reverse osmosis, and its advantage is that it can not only intercept organic molecules with molecular weight of several hundred, but also have different retention capacity for ions in different valence states. The mass transfer model of nanofiltration membrane (space charge model, fixed charge model and hybrid model, etc.) was introduced, the advantages and disadvantages of various preparation methods of polymer nanofiltration membrane were compared, the process of preparing polymer composite nanofiltration membrane by interfacial polymerization, the materials used in interfacial polymerization, the influencing factors of membrane properties and the characteristics of the method were introduced, and finally the research of nanofiltration technology would develop in the direction of new nanofiltration membrane development, integrated process development and process optimization.