Abstract: 【Objective】The response surface method was used to optimize the process conditions of ultrasonicassisted extraction of polyphenols from Musella lasiocarpa(Franch.),and the antioxidant activities of M. lasiocarpa polyphenol extract(MLPE) were further evaluated,to provide theoretical support for further development and utilization of M. lasiocarpa.【Method】Ultrasonic power(X₁),extraction temperature(X₂),extraction time(X₃) and solid-liquid ratio (X₄) were selected as experimental factors,and polyphenol yield(Y) was the response value,response surface methodology was conducted to optimize conditions of ultrasonic-assisted extraction from M. lasiocarpa petal on the basis of single factor experiments. The antioxidant activity of the polyphenol extract was evaluated by the scavenging ability of 1,1-diphenyl-2-trinitrophenylhydrazine(DPPH) free radicals and 2,2-diazo-bis(3-ethyl-benzothiazole-6-sulfonic acid)diamiammonium salt(ABTS) and total antioxidant capacity(FRAP).【Result】The effect of each factor on the extraction rate of polyphenol from the M. lasiocarpa was X₂>X₃>X₁>X₄. The effect of interaction between X₁X₂ and X₁X₃ on the polyphenol extraction rate were extremely significant(P<0.01),while the effect of interaction effect of X₂X₃ was significant (P<0.05). The optimized model equation was Y=100.73-4.87X₁X₂-5.03X₁X₃-4.09X₂X₃-11.13X₁²-9.06X₂²-12.05X₃²-10.46X₄²,and the optimal extraction process parameter for polyphenols from the M. lasiocarpa were ultrasonic power of 360 W,extraction temperature of 55℃,extraction time of 30 min,and liquid-solid ratio of 1:20(g/mL). Under these optimal conditions,the extraction amount of polyphenols from M. lasiocarpa was 10.51 mg/g,which was consistent with the theoretical value of 10.08 mg/g. Results from antioxidant assays showed that the half maximal inhibitory concentration (IC₅₀) values of DPPH and ABTS radical scavenging activity were 20.03 and 39.68 μg/mL,respectively,with a FRAP values of 47.540 μg/mL,antioxidant ability were higher compared to quercetin.【Conclusion】This study indicated that MLPE extracted by ultrasonic-assisted extraction has good antioxidant activity,which can be developed into a edible,safe and natural antioxygen.