Abstract: In order to explore new anthocyanins resources, the ultrasonic assisted extraction of anthocyanins from seed coat of red kidney bean ( Phaseolus vulgaris L.) was optimized by response surface methodology based on the single factor experiments and the antioxidative activity of the crude extract was evaluated. According to the results, the optimal extraction solvent was40% ethonal ( modified to p H1 by hydrochloric acid) , and the highest extraction yield of 185.57 mg anthocyanins/100 g seed coat powder was achieved at an extraction temperature of 68 ℃, an ratio of raw material to solvent of 1 ∶ 24 ( g/m L) , an extraction time of 78 min and the ultrasonic power was 160 W.The results of antioxidation experiments showed that the highest scavenging capacity of anthocyanins against ABTS free radical, DPPH free radical was 68.11%, 90.66% respectively and the ferric reducing antioxidant power was in direct proportion to the anthocyanins concentration. The optimization of ultrasonic extraction of anthocyanins from seed coat of red kidney bean was reasonable and scientific, and the anthocyanins had stronger antioxidant activity.