Abstract: OBJECTIVE To observe the in vitro antibacterial effect of povidone-iodine disinfectant on biofilms of planktonic state of Staphylococcus aureus and the S.aureus on surfaces of titanium alloy plate so as to provide guidance for clinical study. METHODS By means of suspension quantitative germicidal test, the antibacterial activity of povidone-iodine against the planktonic state of S.aureus was observed, the 24-hour bacterial biofilm model was established on the surfaces of titanium alloy plate, the structure of bacterial biofilm was observed by using laser scanning confocal microscope and scanning electron microscope, and the antibacterial activity of povidone-iodine against the bacterial biofilms on the surfaces of titanium alloy plate was observed by means of viable counting method. RESULTS Under laboratory conditions, all planktonic S.aureus strains could be killed in 30 seconds with povidone-iodine with the available iodine concentrations of 0.1%, 0.2%, 0.3%, 0.4% and 0.5%. The mature biofilms could be displayed under both CLSM and SEM. After 5 min of immersion in povidone-iodine, the CFU viable counts on titanium alloy disk were constantly decreased with the increase of concentration of povidone-iodine, and the CFU count was 0 after the biofilms were immersed in 0.5% povidone-iodine for 10 min. CONCLUSION The povidone-iodine has antibacterial activity against not only the planktonic state of S.aureus but also the 24-hour biofilms of S.aureus on the surfaces of titanium alloy plate, the antibacterial activity is enhanced with the increased of concentration of povidone-iodine and extension of effecting time, indicating that the bacteria within the biofilm can be completely killed after more than 10 min of immersion in 0.5% povidone-iodine.