Almond shell-modified urea–formaldehyde resins (AUF) were prepared in this study. The optimal addition amount of almond shells was selected by formaldehyde emission and wet shear strength. The activation energy (E_a) values at different conversion rates and the reaction kinetics were estimated based on the Flynn–Wall–Ozawa method. The results indicated that almond shells can significantly reduce the formaldehyde emission and increase wet shear strength and thermal stability of the urea–formaldehyde resin adhesive. The optimal addition of almond shells is 3 wt %.