Abstract: Technological conditions of extraction of Lentinan with ultrasonic extraction are optimized for developing and utilizing the resource of Mushrooms by using the response surface method（RSM）. Firstly, single factor experiment was investigated, and then based on single factor experiment, a 3-factor, 3-level Box-Benhnken experiment was designed, in which ultrasonic power, ultrasonic time and the ratio of solid to liquid were chosen as influencing factors, and the yield of polysaccharide was selected as response value. The result shown that the regression model fit well with experimental data, and it can well predict the polysaccharideyield of Lentinan. The optimum conditions of ultrasonic extraction were ultrasonic power of 300 W, ultrasonic extraction time of 25 min and solid-to liquid ratio of 1:30, and the polysaccharide yield was 25.71%. Compared with the theoretical value（25.55%）, it has a smaller relative error at 0.63%. Compared with traditional method, ultrasonic extraction method is more efficient and less time consuming, so it is the ideal extraction method of Lentinan.

Key words: hot water extraction, ultrasonic assisted extraction method, polysaccharide yield, response surface optimization, single factor experiment