The soybean protein was hydrolyzed using mucor strain, and the hydrolysis degree, protein recovery rate and peptide nitrogen content of the enzymatic hydrolysate under different hydrolysis conditions were also determined. The changes of taste substances such as proteins under different conditions were analyzed. On the basis of single factor experiment, Box-Behnken response surface methodology was used to optimize the processing conditions of mucor proteinase hydrolysis of tofu billet with hydrolysis degree as the response value, material-liquid ratio, enzymatic hydrolysis temperature and enzymatic hydrolysis time as the influencing factors. The results showed that the optimum conditions were enzymatic hydrolysis temperature of 34.3 ℃, enzymatic hydrolysis time of 96 h, ratio of material to liquid of 1:2.2, and no pH adjustment. Under this condition, the degree of hydrolysis was found to be 5.62%, compared with the model predicted value of 5.637%, there was little difference in result. The corrected correlation coefficient R2=0.9919, which indicated that the response surface model fits the actual test well, and it can explain 99.19% of the response value change. The order of the effect of three factors on the degree of hydrolysis of soybean protein was enzymatic hydrolysis temperature > liquid-material ratio> enzymatic hydrolysis time. It provided a certain theoretical support and data reference for using the enzyme system produced by mucor natural fermentation to dezymolyze soybean protein.