Abstract: The ultrasonic assisted extraction of isovitexin from Zizyphi spinosae semen was optimized. On the basis of single factor experiment,ultrasound time,ultrasound power,ethanol volume fraction and liquid-solid ratio were selected as independent variables,the yield of isovitexin was used as the response value. The 4 factors and 3 level response surface tests were designed by Box-Behnken experiment. The results showed that the ultrasonic extraction conditions of optimization by response surface methodology was as follows:Ultrasound power 419 W,liquid-solid ratio 16:1 mL/g,ultrasound time 61 min,ethanol volume fraction 73.70%. The influence factors on the yield of isovitexin was as follows:Ethanol volume fraction > ultrasound time > liquid-solid ratio > ultrasound power. The relative error between the predicted optimum yield 0.236% and the actual yield 0.241% was 2.075%,which proved that the theoretical predicted value of the model fitted well with the actual value. In this study,the ultrasound assisted extraction technology of isovitexin was optimized to provide a reference for ultrasonic-assisted extraction of flavonoids.