Plant proteins are recognized for their environmental benefits, including a low carbon footprint, renewability, abundant availability, and cost-effectiveness, making them ideal raw materials for biomass-based ecofriendly adhesives. In this study, a green, environmentally friendly soybean protein-modified phenolic resin was synthesized by treating soybean meal with sodium hydroxide/urea aqueous solution. FTIR analysis results of PF and U-SMPF resins shows that the peptide chain structure of soybean protein was incorporated into the phenolic resin, undergoing co-condensation with phenol and formaldehyde to form co-condensed compounds. The 30% U-SMPF resin shows the highest bonding strength at 0.92 MPa, suggesting that the monosaccharides generated from soybean meal treated with sodium hydroxide/urea solution have a limited effect on the bonding strength of the co-condensed resin.