The work aims to study on the modification of soybean protein adhesive and improve the bonding strength of the adhesive through modification approach. Acrylamide-modified soybean protein degraded in alkaline environment was used to prepare the adhesive. The bonding strength of the adhesive was tested. Optimal technological conditions were determined by orthogonal test. When acrylamide (AM)∶maleic anhydride (MA)∶APS (30%) = 12∶50∶10 and pH=11, the adhesive had the best bonding strength (0.91MPa), and met the requirements on category II plywood specified in GB/T 9846—2004. In conclusion, modified protein adhesive containing 24%～28% solid can be obtained through the experiment.