Abstract: Objective : To optimize ultrasonic- assisted extraction techniques of total flavonoids from fruits of Osmanthus fragrans Lour. by using response surface method. Methods:Ethanol concentration, ultrasonic time and liquid-solid ratio served as independent variables while the total flavonoids served as the dependent variable. Based on multiple linear regression and binomial expression, central composite design and response surface method were employed to optimize the extracting process. Results:The optimized extraction conditions were ethanol concentration (66%) , ultrasonic time (26min) and liquid-solid ratio (25m L/g) , and affected the total amount of extraction (6.99%) . Conclusion:The optimum process, simple in methodology, yet yields reliable results.