Abstract: Effects of each factor on the ultrasonic-assisted enzymatic enhancing autolysis of yeast from waste brewert were studied. After single-factor experiments, four-factor three-level Box-Behnken model was established by using Statistica 8.0 software, and the quadratic regression model was gotten. Optimal conditions of ultrasonic-assisted enzymatic enhancing autolysis of yeast from waste brewer were:ultrasonic time 45min, ultrasonic power 720W, enzyme concentration 1.8%, the start temperature 25℃, the predicted yield of amino acid nitrogen was 3.98%, the real one was 3.92% which was close to the predicted value. Results indicated that the experiment design and analysis method was reliable and the model could be used in the process of ultrasonic-assisted enzymatic enhancing autolysis of yeast from waste brewer.