Single factor experiments were conducted to explore the influence of different effects on soybean protein enzymolysis. Based on this, the model of proteolytic digestion process was built according to the grey correlation analysis method to expand application of grey correlation analysis method in food field and provide quality soybean polypeptide resources for the food industry. Alcalase alkaline protease (4.4×104 U/g) was used to enzymatic hydrolysis soybean defatted soybean meal to preparate soybean peptides. The correlation coefficient of reaction pH, reaction temperature, reaction time, soybean defatted soybean meal addition and Alcalase alkaline protease addition were calculated by grey correlation analysis method. Significant size of various factors: pH > temperature > concentration of substrate > addition of enzyme > reaction time. Degree of hydrolysis was basic consistent with degree of prediction hydrolysis by experimental verification. The experimental conclusion proves reliable. The optimum technological parameters were determined as follows: the reaction pH value was 9.0, the reaction temperature was 55 ℃, the reaction time was 3h, the addition of defatted soybean meal was 5% (m/V), and the addition of Alcalase alkaline protease was 1 500 U/g. Under those conditions, degree of hydrolysis (DH) was 13.53%.