Abstract: In order to reduce usage of formaldehyde content adhesives and popularize environment friendly adhesive application in plywood, the modified soy-based adhesive (SBA) was prepared as a new kind of waterproof adhesive to make plywood. The hot-press conditions were optimized by using orthogonal experimental design. The curing mechanism of soy-based adhesive was investigated by FTIR，XPS and TG-DTG. The results showed that (i) hot-press temperature, pressure and time could affect the bonding strength and the contribution order was hot-press temperature > hot-press pressure > hot-press time; (ii) under the optimized conditions (hot-press temperature 140℃, hot-press pressure 1.0 MPa and hot-press time 4.69 min), the water-resistant bonding strength of plywood was up to 0.91MPa, which meets the requirement of plywood type II in GB/T 9846-2004. Fourier transform infrared spectroscopy (FTIR) analysis showed the SBA was crosslinked by chemical reaction during the curing process, the crosslinking gave rise to the increase of amino bonds and reduce of hydrophilic groups. X-ray photoelectron spectroscopy (XPS) analysis showed that during the curing process amide reaction occurred and accompanied with amination which induced the formation of 3D structure of SBA. And the TG-DTG results showed that SBA cured completely when the temperature was in the range of 140-150℃, above this range it could result in decomposition of SBA. The research can provide a reference for SBA application in plywood industry.