Abstract: The surface modification of nano SiO₂ particles with γ-aminopropyl triethoxysilane(KH550) was carried out, The SiO₂-wood fiber/polyvinyl chloride(PVC) composites were prepared by melt-mixing with wood fiber, PVC and other additives. The structure and properties of SiO₂ particles and SiO₂-wood fiber/PVC composites were tested and characterized by FTIR, SEM and STA.FTIR analysis shows that the surface of SiO₂ particles bond KH550 characteristic organic functional group, KH550 successfully grafts to the surface of SiO₂ particles. SEM analysis shows that the modified nano-SiO₂ particles can be dispersed uniformly in the SiO₂-wood fiber/PVC composites with a particle size of about 100 nm; After adding the modified SiO₂ particles, the combination of wood fiber and PVC is more tight, the hole gap is reduced. When the mass ratio of nano SiO₂ to wood flour mass is 10%, 8%, 10%, the mechanical property of the SiO₂-wood fiber/PVC composites will reach the optimal state:elastic modulus, tensile-strength and impact-strength are 4.66 GPa, 31.12 MPa and 4.11 kJ/m², increased by 50.29%, 28.91% and 16.65%, respectively.