In order to optimize the enzymatic digestion process of soybean meal， soybean meal peptides of moderate molecular mass and easy to digest and absorb were obtained. In this study， the effects of trypsin， alkaline protease， neutral protease， papain and keratinase on the hydrolysis degree， peptide yield， molecular mass and bitterness value of soybean meal during the semi-solid enzymatic digestion process were compared. A single-factor experiment was carried out using trypsin， which has a better enzymatic effect， and three conditions (liquid to solid ratio， soybean meal quantity and temperature) were selected to optimize the preparation process. The results showed that the peptide was produced in high yield (18.87%) by trypsin digestion at 40 mg/g， 36 h， 1 mL/g liquid to solid ratio， 30 g soybean meal and 50 ℃.