Astilbin is the main active ingredient of Smilacis Glabrae Rhizoma (SGR) of the same origin of medicine and food,which has a variety of biological activities such as antioxidation,antibacteria and immunosuppression.In this paper,the effect of the content of astilbin on the antibacterial activity of SGR ethanol extracts was researched.With 70% ethanol as solvent,SGR extraction was prepared by ultrasonic wave.The contents of astilbin in the extracts were measured by HPLC.Two dilution method and Oxford cup method were used respectively to determine the bacteriostatic effect of astilbin and the extracts on Staphylococcus aureus,Escherichia coli and Bacillus subtilis,to explore the dose-effect relationship between the content of astilbin in the extracts and its antibacterial effect.The results showed that the MIC values of the extracts for Escherichia coli,Staphylococcus aureus and Bacillus subtilis were 10,2.5 and 0.625 mg/mL,respectively,which were lower than the positive control group of nisin (5 mg/mL).The concentration of the extracts and the content of astilbin had obvious influence on the antibacterial effect of the three strains,and showed a certain dose-effect relationship.There may be a combined bacteriostasis between astilbin and other components in the extracts,especially for Staphylococcus aureus and Bacillus subtilis.