Abstract: Response surface methodology was used to optimize the ultrasonic-assisted extraction process of flavonoids from passion fruit pulp and peel. The antioxidant activity of flavonoids extracted under the optimal process conditions was evaluated by detecting the scavenging rate of hydroxyl radical and superoxide anion. The results showed that the optimal extraction process of flavonoids from passion fruit pulp was as follows:Solid-liquid ratio 1:8 g/mL,ultrasonic time 51 min,and ethanol volume fraction 70%,and the best technology for pericarp is solid-liquid ratio 1:47 g/mL,ultrasonic time 41 min,ethanol volume fraction 70%. Under the optimum extraction conditions of pulp and peel,the yield of flavonoids was 1.04% and 2.71%,respectively. When the concentration of flavonoids reached 0.285 mg/mL,the scavenging rates of hydroxyl radical reached 51% and 55% respectively,and the clearance rate of superoxide anion reached 51% and 58% respectively,with indicated that flavonoids in the pulp and peel of passion fruit had good antioxidant activity.