The purpose of the study was to manufacture plywood using starch adhesives modified by isocyanate, the influence factors on the bonding strength and water resistance of starch adhesive were studied by different solid content, adding additives and adding isocyanate. X-ray photoelectron spectroscopy (XPS) analysis was used to characterize the chemical structure of bonding interface. The results show that the bonding strength of starch adhesive was increased significantly when solid content increased to 50%. Bonding strength and water resistance were improved significantly by adding additives and isocyanates to starch adhesive. The analysis of XPS indicated that the chemical bonding derived from the reactions of isocyanate was the key factor to increase bonding strength and water resistance.