Soy-based resins have recently attracted great attention as adhesives in the wood composite industry. This article is focusing on hydrolysis and modification of soy protein concentrates to formulate soy-based resins for wood composites. The soy-based resins have been evaluated in terms of bondability on wood substrates and bonding performance in plywood products. The performance of plywood was found to meet the relevant CSA standard (Canadian Standard Association) requirements under both of dry and wet conditions, if the soy-based resins were obtained from low hydrolyzed soy flour. Hydrolysis is an effective and efficient tool for reducing the viscosity of soy resins. However, hydrolysis also reduces the bond strength of soy-based resins as hydrolysis cleaves the macromolecules of soy proteins into smaller molecules. Modified soy-based resins have a certain potential for production of interior- and exterior-used plywood.