Polypeptide was used to improve the water resistance of konjac glucomannan (KGM)-chitosan-based wood adhesives. With identical solid content, the tensile strength in wet state was increased by the addition of polypeptide and amaximum tensile strength of 2.34MPa was reached. To examine the physical and chemical changes induced by the addition of polypeptide, the structure, viscoelasticity, morphology, and miscibility of the adhesive blends were determined by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, rheometry, and scanning electron microscopy. Results indicated improvements in mechanical properties were related to the formation of intermolecular hydrogen bonds and covalent bonds between KGM, chitosan, and polypeptide, which was enhanced by increasing the polypeptide concentration. Good miscibility existed between KGM, chitosan and polypeptide, as well as good wettability between the adhesive blends and wood veneer.