Abstract: In order to investigate the effect of ultrasound-assisted water extraction on the extraction rate of polysaccharides from Padus napaulensis,single factor experiments were carried out to study the ultrasonic power,ultrasonic time,extraction temperature and liquid-to-solid ratio. On this basis,the process parameters were optimized by response surface method,and the antioxidant activities of raw polysaccharides from Padus napaulensis in vitro were analyzed. The results showed that the extraction rate of raw polysaccharides could reach 12.55%±0.31% when the optimum extraction technology of polysaccharides was ultrasonic time of 6 min,ultrasonic power of 97 W,extraction temperature of 86℃,extraction time of 150 min and liquid-to-solid ratio of 40 mL/g,which was only less 0.23% than the predicted value. The contents of polysaccharides reached(413.75±0.41) mg/g,which indicated the model could predict the actual extraction rate well. The IC₅₀ of polysaccharide solution of Padus napaulensis for DPPH·,·OH and total reduction ability were 0.0203 and 1.44 mg/mL,respectively,and in which had dosage-effect relationship and good antioxidant activity in vitro. Therefore,it was feasible to optimize the extraction process of polysaccharides by ultrasound-assisted water extraction with response surface method,and could provide theoretical basis for further development and utilization of Padus napaulensis.