Abstract: In order to solve the problems of low bonding strength and high viscosity of soybean protein adhesive and toxic volatile substances such as formaldehyde in the adhesive, a new type of green soybean protein adhesive was prepared to meet the requirements of indoor use of plywood and glued products. In this study, defatted soybean protein powder was taken as the main research object, and alkaline protease was used as the modifier to explore the effects of different enzyme additions, pH, enzymolysis temperature, and enzymolysis time on the bonding strength of soybean protein adhesive. The optimum reaction conditions of soybean protein adhesive were obtained through orthogonal design experiment enzymolysis as followos: alkaline protease 10 000 U·g^-1, pH9.5, temperature 60 ℃ and time 100 min. Compared with unmodified soybean protein adhesive, the viscosity of modified adhesive decreased from 2 400 s to 13 s, and the bonding strength was increased from 0.74 to 0.98 MPa, meeting the requirements of the national standard GB/T 9846-2004 Class II plywood. The experiment shows that the alkaline protease modified soybean protein adhesive has a good application prospect in the field of plywood production.