Abstract: In order to clarify the extraction methods of amygdalin from bayberry thinning fruits kernels， the extraction process was studied using the bayberry(Myrica rubra Sieb. et Zucc. var. Ding ao) fruits by ultrasonic technology. Based on the singlefactor and 2level extraction experiment， a threefactor and threelevel experimental strategy was designed with the DesignExpert 80 software using the ethanol concentration， solidliquid ratio and the extraction temperature as the experimental factors and the extraction yield as response value. The predictable model of quadratic regression equation was obtained. The optimum extraction conditions were concluded as follows: ethanol concentration 27%， solidliquid ratio 1∶45 (m/V)， extraction time 20 min， extraction temperature 44℃， and ultrasonic power 250 W. In this condition， the predicted value of amygdalin extraction yield by the model was 9403%， which was in good agreement with the experimental value of 9380%．

Key words: bayberry fruit thinning, amygdalin, ultrasonic extraction, response surface optimization