The invention discloses a method for modifying a chitosan membrane by using a biomimetic coating prepared from a phosphorylcholine polymer containing epoxy and a phosphorylcholine polymer containing an amino group. The method comprises the steps: carrying out simple solution free radical polymerization on a vinyl monomer containing a phosphorylcholine hydrophilic group and a vinyl monomer containing epoxy or a vinyl monomer containing an amino group to synthesize the phosphorylcholine polymer containing epoxy and the phosphorylcholine polymer containing the amino group; dissolving the two phosphorylcholine polymers into a polar solvent; coating the surface of the chitosan membrane; and drying the chitosan membrane, and carrying out heating treatment in distilled water to prepare a crosslinked biomimetic coating with a structure simulating an outer cell membrane. The method is simple in preparation and convenient to operate, and a novel approach is provided for obtaining the crosslinkedbiomimetic coating with excellent blood compatibility. The modified material with the structure simulating the outer cell membrane is to achieve a wide application prospect in fields such as blood purification, in-vivo implantation materials, tissue engineering, drug sustained release and biosensors.