Soy protein (SPI) adhesives are non-toxic and eco-friendly that can potentially replace traditional formaldehyde-based adhesives to ease toxic gas emissions.The development of strong and toughness SPI adhesive benefits its bonding stability but is challenging. In this study, inspired by nacre structure, a soft-hard double network structure was constructed in SPI adhesive. The triglycidylamine (TGA) cross-linked protein served as the hard phase to provide cohesion. In addition, the self-synthesizing epoxidized rubber (ER) as soft phase cross-linked protein and enhanced the interfacial force between hard and soft phase to dissipate energy during fracture, which improved the toughness of adhesive. The results showed that: compared with original SPI adhesive, the residue rate of SPI/4%TGA/3%ER adhesive increased by 7.9%, and the moisture absorption rate decreased by 16.7%. The dry and wet shear strength of the plywood prepared by SPI/4%TGA/3%ER adhesive increased by 58.9% and 160.4% to 1.86 and 1.38 MPa, which was higher than commercial polyamide-epichlorohydrin modified SPI adhesive. The elongation at break increased by 55.2%-45%, the fracture energy increased by 233% to 2.96 MJ/m 2 , and the cracks on the adhesive surface disappeared, indicating that the strength, toughness, and water resistance of the adhesive were significantly improved. In this research, a soft-hard double network structure is constructed in a bio-based adhesive to obtain excellent performance, this eco-friendly adhesive opens up a new way to replace harmful formaldehyde-based adhesives.