The invention belongs to the technical field of composite nanofiltration membranes, and discloses a preparation method of a high performance nanofiltration membrane based on a constructed multi-network structure. The preparation method comprises following steps: soaking a polysulfone base membrane in an alcohol solution (30%) for 30 minutes; painting a water solution, which contains dopamine and one or more water-soluble polymers, on the polysulfone base membrane, making dopamine carry out auto-polymerization to form a membrane, doping the water-soluble polymers into the dopamine membrane to form a three dimensional network structure, drying the base membrane in the shade, painting a water phase solution that contains dopamine on the base membrane, drying the base membrane in the shade, painting a poly(acyl chloride) oil phase solution on the base membrane, and finally subjecting the coated base membrane to a post treatment, which is performed at a certain temperature, to obtain the nanofiltration membrane. The nanofiltration membrane prepared through interfacial polymerization has a good retention ratio, moreover, water flux is largely improved, the reproducibility is good, and the preparation cost is low.