The main reason for biomaterial-related refractory infections is biofilm formation caused by bacterial adhesion on the surface of materials. Silver-hydroxyapatite (Ag/HA) nanocomposite coating can inhibit the formation of biofilm, but its mechanism is not clear. In this study, we will determine the amount of biofilm on the Ag/HA composite coating, detect the sustained release rates of silver ions in simulated body fluid, the effects on the biofilm formation of bacteria and the expression of genes related to biofilm formation of S aureus.