Abstract: Carrot leaves have aroma and are not easy to be infected by pests and diseases,which are one kind of good raw material for green food.In order to improve the utilization of carrot leaves,the extraction process conditions of total flavonoids from carrot leaves were optimized by ultrasonic-assisted aqueous two-phase extraction technology with the extraction yield as evaluation index.Based on the single factors experiments,the involving factors were optimized using Box-Behnken response surface methodology and a quadratic polynomial regression equation was established for the extraction yield of total flavonoids and ethanol concentration,ultrasonic temperature,liquid to material ratio and ammonium sulfate concentration.Experimental results of single factors showed that the extraction yield of total flavonoids increased firstly and dropped subsequently with the increase of the above four related factors.The optimum extraction conditions of total flavonoids from carrot leaves by the ultrasonic-assisted aqueous two-phase method were as follows:ethanol concentration of 64.39%,ultrasonic temperature of 61.32℃,liquid to material ratio of 34.48 mL/g and ammonium sulfate concentration of 0.41 g/mL.The revised optimum process conditions were:ethanol concentration of 64%,ultrasonic temperature of 61℃,liquid to material ratio of 34 mL/g and ammonium sulfate concentration of 0.41 g/mL.The extraction yield of total flavonoids could be up to 4.956% and the relative error was 0.52% compared to the predictive value,which testified that the regression model was fitted well with the experimental data.It was concluded that ultrasonic-assisted aqueous two-phase extraction of total flavonoids from carrot leaves optimized by Box-Behnken response surfacemethodology had high accuracy and reliability.