Preparation method of high-performance composite nanofiltration membrane

The invention provides a preparation method of a high-performance composite nanofiltration membrane, which comprises the following steps: S1, dissolving a water-phase monomer in pure water, fully stirring until the water-phase monomer is dissolved to obtain a water-phase solution, and preserving in a dark place; s2, adding an organic phase monomer into an organic solvent, fully stirring until the organic phase monomer is dissolved to obtain an organic phase solution, storing in a dark place, and preparing n organic phase solutions with different concentrations by using the same organic phase monomer; s3, immersing the surface of the porous support membrane in the aqueous phase solution, then taking out the porous support membrane, and removing the aqueous phase solution until no residual liquid drops exist on the surface; step S4, pouring n organic phase solutions with different concentrations on the surface of the porous support membrane by several times to carry out interfacial polymerization reaction by se