Abstract:The extraction conditions of ultrasonic method were studied on flavonoids from shells of passion fruit by single factor and orthogonal test.The flavonoids were purified by using column chromatography with polyamide.The antioxidant activity of flavonoids was studied by using the pyrogallol autoxidation method，DPPH and salicylic acid（SA），and vitamin C（VC）in the same concentration was compared as control group.The results showed that the optimal extraction conditions of flavonoids from shells of passion fruit were 60%ethanol as extraction agent，the temperature of 50 ℃，solid-liquid ratio of 1 ∶30（g/mL），ultrasonic extraction time of 40 min and ultrasonic power of 240 W.Under this optimal condition，the flavonoids content was 8.084 0 mg/g.The purity of the sample and the recovery respectively were 20.08 % and 82.95 % with 70 % ethanol as the eluant by using polyamide column chromatography.The scavenging rate of flavonoids to hydroxyl radicals was 58.66%，the maximum scavenging rate of DPPH radicals reached to 93.81%，and the maximum clearance rate of superoxide anions reached to 82.61%.The results showed that flavonoids from shells of passion fruit exhibited high antioxidant activity and were an ideal natural antioxidant.The experimental results could provide some scientific basis for the comprehensive utilization of passion fruit.