Abstract:The present study aimed to optimize the extraction process of polyphenols from Camellia petelotii（Merrill）Sealy and analyze their antioxidant activity.An ultrasonic-assisted extraction method was used to extract polyphenols from Camellia petelotii leaves.The effects of ethanol concentration，extraction time，extraction temperature and ratio of material to liquid on the extraction yield of polyphenols were investigated.In addition，the extraction process was optimized based on orthogonal experimental design.The scavenging rates of 1，1-diphenyl-2-picrylhydrazyl（DPPH）and 2，2-azino-bis（3-ethylbenzthiazoline-6-sulfonic acid）（ABTS）free radicals，and total antioxidant capacity were used as indices to evaluate the antioxidant activity of polyphenolic extracts from Camellia petelotii leaves in vitro.The results showed that the optimal extraction parameters of polyphenols from Camellia petelotii leaves were an ethanol concentration of 90%，extraction time of 30 min，extraction temperature of 35 ℃，and material-liquid ratio of 1∶50（g/mL），which achieved a polyphenol extraction yield of 295.82 mg/g.The antioxidant activity results showed that polyphenols from Camellia petelotii leaves exhibited good total antioxidant capacity and a strong scavenging effect on DPPH and ABTS+free radicals，and their IC50values were 0.030 9 mg/mL and 0.043 4 mg/mL，respectively；the total antioxidant capacity was 0.82 mmol/L.According to the results，polyphenols from Camellia petelotii leaves could be used as natural antioxidants.