a method of a preparing double - layer antimicrobial coating comprises : placing a plastic substrate into a pvd vacuum equipment for a vacuum process ; rinsing and activating the substrate when the vacuum level reaches 10 − 2 ; coating a metal film onto the activated substrate by the vacuum process ; spraying an antimicrobial intermediate coating onto the metal film ; and then coating an antimicrobial metal film by pvd to obtain a double - layer antimicrobial layer . the coating has two antimicrobial layers , and includes bores because the density of the coated film layer produced by pvd is low , so that the antimicrobial agent of the antimicrobial intermediate coating can pass through the bores and move to the surface of the coating and the surface of the antimicrobial coating , so as to kill the bacteria or suppress their grown . the method is very suitable for the sanitary , electronics , electrical appliances and the automobile industry .