Abstract: The optimum extraction condition of polysaccharides of Lycium ruthenicum of Jingle was determined and its antioxidant acitvity was studied. Polysaccharides from Jingle's Lycium ruthenicum were extracted with water solution by ultrasonic-assisted method. The effects of liquid-to-material ratio, ultrasonic power, ultrasonic time and ultrasonic temperature on the yield of polysaccharide from Jingle's Lycium ruthenicum were studied at first. Then the Box-Behnken design principle and four-factor three-level response surface methodology were adopted, the results were obtained with the yield of polysaccharides as the response value, and its antioxidant activities were studied. The result showed that the optimized conditions were ultrasonic power 360 W, liquid-to-material ratio 40:1 (mL/g), extraction temperature 70℃, extraction time 50 min. Under such conditions, the polysaccharide yield was 13.89%, and the relative error was 0.22%, which was well matched with the predicted yield. The scavenging activity of 2, 2-diphenyl-1-picry-hydrazyl radicals, hydroxyl radicals, ABTS⁺ radicals and reducing capacity showed that its extracts had dose-effect relationship with the increasing of concentration. The IC₅₀ of DPPH·,·OH and ABTS⁺·were 0.125, 6.00 and 0.40 mg·mL^-1, respectively. Therefore, it would provide a theoretical basis for further rational development and utilization of Jingle's Lycium ruthenicum.