Abstract: The Response Surface was used to optimize the extraction process of Sophorae flavescentis radix antibacterial formula.The inhibition rate of Staphylococcus aureus was set up as response value.When single factors such as soaking-time,extraction duration,reflux temperature,ratio of liquid to solid,ethanol concentration had been tested,the key factor was chosen as the variable of the Response Surface Methodology.The process of optimal extraction was determined by prediction of mathematical model and verification of experiment ,which is as followed:80.5% of ethanol concentration,1.6 h of extraction duration,95 ℃ of reflux temperature.The inhibition rate of the best process is 94.29% while the concentration of raw herbal is 0.003 g/mL.The verification result is stable and the deviation from the prediction is less than 2%，which makes the extraction reasonable and feasible.Under the optimized process,the extract has a good inhibitory effect on Bacillus subtilis,and has less inhibitory effect on Escherichia coli.

Key words: bacteriostat, response surface methodology, extraction process, ethanol reflux extraction