Abstract: OBJECTIVE To investigate antibacterial activity and mechanism of Tibetan medicine Liuweidingxiang pills against Staphylococcus aureus， and provide theoretical basis for clinical application. METHODS M-H agar-punching method was adopted to research antibacterial activity of Liuweidingxiang pills against Staphylococcus aureus， and the minimum inhibitory concentration (MIC) was measured by broth dilution method. The absorbance OD_600nm of culture medium mixed with medicine was continuously recorded for 36h and growth curve of S. aureus was drawn. Furthermore， the antibacterial mechanism was explored using scanning electron microscopy and cell wall permeability test. RESULTS The diameter of inhibition zone was (21.8±2.36) mm at 800 mg/mL， and the MIC was between 12.5 mg/mL and 25 mg/mL. This medicine had significant inhibition to bacterial proliferation. The structure of bacterial cell was changed and the permeability of cell wall was increased. CONCLUSION Liuweidingxiang pills had significant antimicrobial effect on multidrug-resistant S. aureus， which implied potential value in clinical application.