Wood polymer nanocomposite (WPNC) was prepared by impregnation of styrene-acrylonitrile copolymer (SAN) of 2:3 molar ratio, vinyl trichlorosilane (VTCS) modified ZnO nanoparticles and glycidyl methacrylate (GMA) as a cross-linking agent into cellular structure of wood. The surface modification of ZnO nanoparticles and the properties of the WPNC were investigated by XRD, FTIR, TGA, SEM and TEM. The mechanical properties including modulus of rupture (MOR), tensile strength and hardness, and multifunctional properties involving UV resistance, water resistance, dimensional stability and thermal stability were studied. The nano-ZnO particles dispersed uniformly in the polymer filled in the porous structure of wood, as evidenced by SEM-EDX and FTIR, respectively. TEM study showed the homogeneous dispersion of ZnO nanoparticles on the cell wall of wood with SAN polymer matrix.