Abstract: Objective To test the invasion ability of different Staphylococcus aureus（S.aureus）strains. Methods S.aureus strains were incubated with 293 cells at 37℃to infect the 293 cells.Two hours after infection,the medium was replaced with DMEM containing 10μg/mL lysostaphin to kill the S.aureus strains in extra-cellular cells.The cells were trypsinized and lysed with trypsin EDTA and Triton X-100 solution.Cell lysate and supernatant were appropriately diluted and plated on LB agar plates,and colony forming units（CFU）were quantified. Results Clinical isolates of S.aureus 04018 strain had a strong ability to invade 293 cells. Conclusion The ability of S.aureus strains to invade 293 cells by mediating expression of fibronectin-binding protein-FnBP.Different strains have different expression levels and invasion abilities.However,in addition to FnBP protein,other factors may be involved in the invasion of 293 cells.