The invention relates to a method for densifying a bionic coating of amino-acid-containing phosphorylcholine polymers and glutaraldehyde. The amino-acid-containing phosphorylcholine polymers are synthesized from vinyl monomers containing zwitter-ion phosphorylcholine groups and vinyl monomers containing amino acid through simple solution free radical polymerization and then uniformly mixed with glutaraldehyde in a polar solvent, the mixture is applied to the surface of a material required to be modified and then grafted with the vinyl monomers containing the zwitter-ion phosphorylcholine groups, and a bionic cell outer membrane structure coating with high surface phosphorylcholine density can be obtained. The preparation method is simple and uses mild conditions, and a new way is provided to improve the surface phosphorylcholine density of the coating, so that a coating surface with excellent blood compatibility is obtained. The modified material adopting a bionic cell outer membrane structure has broad application prospects in the fields such as blood purification, in-vivo implantation of materials, tissue engineering, sustained drug release, biosensors and the like.