Abstract: To optimize ultrasonic extraction process of saponin from Pleurotus eryngii. In this study,the saponins were extracted from Pleurotus eryngii by ultrasonic extraction. Through single factor test,the effects of ultrasonic extraction time,liquid-solid ratio,extraction temperature and pH of extract on the yield of Pleurotus eryngii saponins were investigated. The Box-Behnken response surface design extraction experiment was used to establish the quadratic regression equation model and variance analysis of each factor. The optimal extraction conditions for ultrasonic extraction of Pleurotus eryngii saponins were obtained:Ultrasonic extraction time 31 min,liquid-solid ratio 11.5 mL·g^-1,extraction temperature 65 ℃,extract pH8.4.Under this condition,the extraction rate of Pleurotus eryngii saponin was up to 3.19%.This optimized extraction process was stable and reliable,which provided a theoretical basis for the industrial preparation of Pleurotus eryngii saponin.