Abstract: To achieve the high extraction efficiency of Auricularia polytricha melanin and evaluate its antioxidant activity.The extraction yield of melanin was used as index,the Box-Behnken response surface method was used to optimize the extracting condition of melanin assisted by ultrasonic and the infrared spectrum,chemical and cellular antioxidant activities in vitro of Auricularia polytricha melanin were evaluated and analyzed.The results showed that the optimal conditions of ultrasonic-assisted melanin extraction were as follows:C_NaOH was 0.34 mol/L,solid-liquid ratio was 1∶30,ultrasonic time was 52 mins,ultrasonic power was 250 W,ultrasonic temperature was 70 ℃.The extraction yield of melanin can reach 9.38%±0.15% under the optimal conditions.The result of infrared spectrum showed that the main absorption peaks of melanin extracted from ultrasonic group was consistent with that extracted from non-ultrasonic group,and the functional groups did not change.The results of chemical antioxidant and cellular antioxidant experiments in vitro indicated that melanin in Auricularia polytrichahad good scavenging activity on 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS),1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical,as well as had obvious protective effect on H₂O₂-induced L02 cell damage.The study confirmed the conditions of ultrasonic assisted extraction of Auricularia polytricha melanin and its antioxidant activities in vitro,which could provide the scientific basis for the development and application of functional products of Auricularia polytricha melanin.