Abstract: With Macheng Chrysanthemum morifolium as raw material, single factor and response surface methodology were used to optimize the ultrasonic assisted extraction of flavonoids, and the antioxidant activity of total flavonoids extracts was evaluated under the optimal conditions. The results showed that the ultrasonic power was 440 W, the ultrasonic temperature was 60℃, and the ultrasonic time was 50 min. Under these optimized conditions, the total flavonoids yield was 7.15%. When the concentration of flavonoids was 0.05 g/L, the total reducing capacity was the strongest, and the absorbance value was 0.341.The free radical scavenging rate of 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) was 81.25% with 0.50 g/L flavonoids, and its IC₅₀ for DPPH free radical was 0.191 g/L, which indicated that it had good antioxidant activity.