Abstract: The aim of this paper was to study the extraction and anti-oxidation activities of flavonoids from Rosa sterilis pomace by ultrasound-assisted enzymatic method.Based on single factor test, the Box-Behnken design was used to optimize the extraction process of flavonoids from Rosa sterilis pomace. The antioxidant activity was determined by DPPH·, ·OH, \rmO_2^-\cdot scavenging assays and reducing power. The results showed that the optimum extraction conditions for liquid-material radio, ethanol concentration, ultrasonic time, ultrasonic power, enzymolysis time, and enzyme dosage were 42 mL/g, 55%, 48 min, 300 W, 40 min and 0.2%, respectively.The yield of flavonoids was experimentally measured to be 87.52 mg/g on average (n=3) under the optimized conditions, which approximatedthe predicted value of 87.78 mg/g, showing the reliability of the optimized process. In DPPH·, ·OH, \rmO_2^-\cdot scavenging assays, the EC₅₀(concentration for 50% of maximal effect, EC₅₀) of the flavonoids extracted from Rosa sterilis pomace were 0.0139, 0.30788, and 0.94291 mg/mL, respectively.The reducing power was less than that of V_C in the range of 0.02~0.5 mg/mL of flavonoids. Ultrasound-assisted enzymatic extraction from Rosa sterilis pomace can provide reference for the resource utilization of Rosa sterilis pomace. The flavonoids extraction extracted from Rosa sterilis pomace has good antioxidant activity and can be developed as a natural antioxidant.