In this study, we had investigated an ultrasonic-assisted method to extract polysaccharides from the B. edulis mycelia using RSM. The results showed that the independent variables (ultrasonic temperature and extraction time), and quadratic terms of ultrasonic temperature and extraction time, and the interaction effects between ultrasonic temperature and ratio of dried mycelia to water had significant effects on the yield of polysaccharides. Ultrasonic temperature was the most significant factor on the experimental yield of polysaccharides. A second-order polynomial model was employed to optimize polysaccharides extraction from B. edulis mycelia by ultrasonic technology. The optimal extraction conditions for the polysaccharides were as follows: ultrasonic tem-perature56 ํC,extraction time of 8.4min,and ration of dried mycelia to water 1:55. Under these condition, the experimental yield of polysaccharides was 15.48%, which was agreed closely with the predicted yield value of 15.53%. The study provided a new and efficient method for the extraction of water-soluble polysaccharides from B. edulis mycelia Further studies on the chemical structures and the bioactive function of polysaccharides from B. edulis mycelia are under process.