Abstract: The surface of wood powder/polyethylene (WP/PE) composites was treated by a combined treatment of sanding then coating with a silane coupling agent and plasma discharge to improve its adhesion properties. To explore the durability of adhesive joint in hot and humid environment, the bonding strength tests and the analysis of FTIR and XPS were used to study the effect of combination treatment on the surface properties changes of WP/PE under boiling environment. The results show that, there are oxygen polar groups generated on the surface of WP/PE after combination treatment, and the chemical bonds between silane coupling agent and composite surface are formed, which improves the bonding performances tremendously. There is no new chemical group generated on the surface of WP/PE with the increase of boiling time, but the chemical environment for the element on the surface changes. The change on surface properties of WP/PE under hot and humid environment will affect the durability of adhesive joint directly. The change degree of surface properties for WP/PE is retarded by combination treatment, and the bonding properties are improved consequently, especially for the water resistance of adhesive joint.