Abstract: Ultrasonic assisted extraction technology of total flavonoids from Xanthoceras Sorbifolia hull,and the antioxidant activities of total flavonoids were studied.The optimum extraction conditions for the total flavonoids were established by single factor experiment and response surface experiment. The results showed that the optimal extraction conditions of the total flavonoids were the raw material granularity of 250~178 μm,the solvent- to- solid of43∶1( m L∶ g),the ethanol concentration of 40%,the ultrasonic time of 19 min,the ultrasonic power of 400 W. Under the conditions,the extraction yield of total flavonoids was 6.502%. The result was consistent with the simulated predictive value.The results of antioxidant activities showed that the total flavonoids from Xanthoceras Sorbifolia hull had strong activity of DPPH free radicals and reducing power,whereas it had weaker activity on scavenging activity on hydroxyl radical.The results can be used to provide theoretical basis for the development and utilization of the total flavonoids of Xanthoceras Sorbifolia hull.