Abstract: Palm oil-based adhesives generally suffer from inherent drawbacks such as low crosslinking degree, loose adhesive layer structure, and weak interfacial bonding, leading to inadequate mechanical properties and poor water resistance of bamboo particleboards. In this study, maleic anhydride was employed to grafting modify the palm oil-based adhesive, and the modified adhesive was applied in the preparation of bamboo particleboards. Fourier transform infrared spectroscopy, differential scanning calorimetry, rotational viscosity measurements, and a T-4 cup test were used to analyze the regulation of the modifier on the adhesive structure, curing behavior, and rheological properties. Single-factor experiments combined with the Box–Behnken response surface methodology were conducted to optimize the preparation parameters of bamboo particleboards. The results show that an appropriate amount of maleic anhydride can graft onto the palm oil-based resin, optimize its molecular structure, improve its rheological behavior, and participate in crosslinking reactions, thereby forming a dense crosslinked network. Maleic anhydride modification significantly enhances the mechanical load-bearing capacity and dimensional stability of bamboo particleboards. As the MA content increases from 0wt% to 30wt%, the modulus of rupture, modulus of elasticity, and internal bond strength increase by 83.6%, 70.6%, and 125.4%, respectively, while the 24 h thickness swelling rate decreases by 46.5%. The modified boards meet the requirements of the P3 grade of GB/T 4897—2015. Response surface optimization yields the optimal preparation parameters as follows: adhesive content of 11wt%, hot-pressing temperature of 158.6℃, hot-pressing time of 300 s, and hot-pressing pressure of 14.55 MPa, under which the model predicts outstanding board performance. Validation experiments show that the relative errors between the measured properties and the predicted values are within 10%, confirming the high prediction accuracy and reliability of the response surface model. This study reveals the microscopic mechanism by which maleic anhydride grafting modification enhances the crosslinking density and interfacial compatibility of palm oil-based adhesives, establishes a synergistic optimization method for the modified adhesive formulation and the hot-pressing process of bamboo particleboards, and provides theoretical basis and technical support for the industrial application of green, formaldehyde-free bio-based adhesives in the field of bamboo-based composites.