Abstract:The ultrasonic technology was employed to extract total polyphenols from high-quality septa of Hetian walnuts produced in Xinjiang，and their in vitro antioxidant activity was analyzed. On the basis of singlefactor experiments，the response surface methodology with central composite design was employed to optimize the liquid-to-material ratio，ethanol concentration，ultrasonic time，and ultrasonic temperature （independent variables），with the total polyphenol yield as the response variable. The results showed that the extraction conditions were optimized as follows：a liquid-to-material ratio of 95∶1 （mL/g），41% ethanol，ultrasonic time of 62 min，and ultrasonic temperature of 40 ℃. Under these conditions，the total polyphenol yield from walnut septa reached 67.025 mg/g. Antioxidant capacity tests showed that at a concentration of 1.0 g/L，the polyphenols from walnut septa significantly scavenged 70.43% and 14.79% of DPPH and hydroxyl radicals，respectively，demonstrating good antioxidant activity.