Polymer grafted inorganic nanoparticles attract significant attention, but pose challenges because of the complexity. In this work, a facile strategy to the graft polymer onto the surface of nanoparticles have been introduced. The vinyl functionalized SiO nanoparticles (NPs) were first prepared by the surface modification of the unmodified SiO using γ-methacryloxy propyl-trimethoxylsilane. The NPs were then mixed with polyvinylidene fluoride (PVDF), which was followed by the Co-60 Gamma radiation at room temperature. PVDF molecular chains were chemically grafted onto the surface of SiO nanoparticles by the linking of the double bond on the NPs. The graft ratio of PVDF on SiO NPs surface can be precisely controlled by adjusting the absorbed dose and reactant feed ratio (maximum graft ratio was 31.3 wt%). The strategy is simple and it should be applied to the surface modification of many other nanoparticles. The prepared PVDF-grafted SiO NPs were then dispersed in the PVDF matrix to make the nanocomposites. It was found that the modified NPs can be precisely dispersed into the PVDF matrix, as compared with pristine silica. The filling content of modifications SiO NPs on the PVDF nanocomposites is almost doubled than the pristine SiO counterpart. Accordingly, the mechanical property of the nanocomposites is significantly improved.