Abstract: On the basis of single factor test,response surface method was adopted to optimize the ethanol extraction process with ultrasonic assistance for total flavonoids of Sambucus williamsii Hance leaves. Moreover,analysis on antioxidant activity of different fractions extracted by solvents with different polarity from the ethanol extract had been conducted for Sambucus williamsii Hance leaves,such as,ethyl acetate,chloroform and butanol.Result showed that,the best process condition of extracting total flavonoids of elderberry leaves with ultrasonic assistance were as follows: ethanol concentration was 70%,solid- liquid ration was 1 ∶ 40,extraction temperature was 70 ℃,extraction time was 60 min. Under this condition,the highest extraction rate of total flavonoids could reach up to 18.67%. The four polarity extraction constituents of Sambucus williamsii Hance leaves,ethyl acetate,chloroform,butanol and water,relative contents of flavonoid from extracts were 54.3%,28.22%,22.01%,9.817%,and they had a certain of scavenging activity against DPPH and ABTS+free radicals. In fact,the scavenging activity of ethyl acetate was the highest,which indicated that,the extraction of ethyl acetate was the optimized part to separate natural antioxidant from Sambucus williamsii Hance leaves.