Abstract:In the present study，polyphenols were extracted from Ginkgo biloba leaves by ultrasound-assisted ethanol extraction.Based on single factor test analysis，four factors（ethanol concentration，material-to-liquid ratio，extraction temperature and ultrasonic time）which affect the polyphenols extraction rate from Ginkgo biloba leaves were investigated.Also，the polyphenols extraction rate was set as the response value，the extraction processes were designed and optimized by Box-Behnken experiment，so as to analyze the effect of main technology parameters on the extraction rate during the extraction process.And the antioxidant activity of polyphenols was measured by the scavenging rate of hydroxyl radicals.The results showed that the Optimum extraction technology of polyphenols from Ginkgo biloba leaves were ethanol concentration 74%，material-toliquid ratio 1：25（g/mL），extraction temperature 62 ℃ and ultrasonic time 30 min.The extraction rate of polyphenols could be up to 8.32% under the optimal condition.The polyphenols extracted from Ginkgo biloba leaves had higher scavenging effect on hydroxyl radicals than VC，and its antioxidant capacity had a positive correlation with the concentration.