Abstract: The Ultrasonic-assisted extraction technology of total flavonoids from lotus root was optimized.The effects of ethanol volume percent, material- to- solvent ratio, ultrasonic power, extraction temperature and time on the extraction yield of total flavonoids ( Y1) and the DPPH free radical scavenging rate of extract ( Y2) were investigated by single- factor experiment. Then, ethanol volume percent, material- to- solvent ratio, ultrasonic power and extraction time were selected to establish the regression mathematical model with four factors.The weighted value ( Y3) of Y1and Y2was used as the index for the optimization of extraction technology.Based on the results from regression model analysis and verification test, the optimized conditions were confirmed to be follows: ethanol volume percent was 50%, material- to- solvent ratio was 1 ∶ 23 ( g /mL) , ultrasonic power was 235W, extraction temperature was 40℃ and extraction time was 76min.Y1, Y2and Y3were respectively tested to be 0.1933%, 49.23%and 122.5% under those conditions, which were independently 0.68%, 1.69% and 0.28% higher than the values predicted by regression mathematical model. The present work can be applied in the development of lotus root flavonoids as a technologic reference.