The conservation and restoration of excavated waterlogged lacquered wooden artifacts remain major challenges in the field of cultural heritage preservation. Although the glyoxal composite dehydration technology has become a mainstream method for the stabilization and reinforcement of such artifacts, effectively addressing dimensional stabilization during dehydration, it also inevitably introduces risks of secondary deterioration. These include lacquer film cracking, warping and detachment caused by differential shrinkage between the wooden substrate and the lacquer layer, as well as persistent weakly acidic conditions (pH≈4-5) resulting from residual glyoxal. Such acidic environments significantly inhibit the activity of laccase involved in the oxidative polymerization of raw lacquer, thereby reducing the bonding strength and durability of traditional lacquer adhesives. To address these issues, this study developed a novel composite adhesive specifically designed for the restoration of glyoxal-dehydrated lacquerware. Natural raw lacquer from Enshi, Hubei Province, was used as the base material, while Tween-20, soy protein isolate (SPI) and nano-SiO₂ were introduced as functional modifiers. An orthogonal experimental design was employed to optimize the formulation. The performance evaluation demonstrated that the optimized adhesive achieved a shear bonding strength of 3.8 MPa, representing an increase of approximately 58% compared with pure raw lacquer. After immersion in a weakly acidic environment (pH≈4) for 30 days, the adhesive retained 91% of its original strength, significantly higher than the 65% retention observed for pure lacquer. Under accelerated aging conditions of 50℃ and 95% relative humidity (RH) for 30 days, the composite adhesive exhibited only a 1.0% weight increase without visible mold growth, whereas pure lacquer showed a 3.0% increase accomplished by slight mildew formation. The cured adhesive film also exhibited excellent chromatic stability, with a color difference (ΔE) of approximately 2.0, which was nearly imperceptible to the naked eye. The practical conservation treatment of excavated lacquerware further verified the feasibility of the adhesive for reattaching detached lacquer films. The restored lacquer layers exhibited strong adhesion, stable morphology, and good chromatic compatibility without secondary warping or delamination. This study provides a new material strategy for the conservation of glyoxal-dehydrated lacquerware and offers a useful reference for integrating traditional lacquer technique with modern functional materials in cultural heritage conservation.