Grafting polyolefin chains onto the surface of silica nanoparticles to form satisfactory polyolefin/silica nanocomposites still remains a challenge, even after the complicated functionalization of the polyolefin chains and surface modification of the silica. In this study, an efficient route for the preparation of polypropylene-grafted nanosilica (PP-g-SiO2) masterbatch was presented through the reactive melt blending of maleic-anhydride-grafted polypropylene (PP-MAH) and amino-functionalized silica (SN-NH2) synthesized by the co-condensation method. The amount of grafted PP chains could achieve to 80.8 wt%. And PP-g-SiO2 exhibited fine dispersion in PP matrix. The shear and extension rheology results of PP/PP-g-SiO2 nanocomposites showed that melt strength of PP could be enhanced remarkably by incorporation of PP-g-SiO2 masterbatch, which revealed the strong interactions between PP-g-SiO2 and PP matrix. These findings provide a facile way to prepare polyolefin-grafted nanosilica, while expanding the potential applications of nanosilica in polyolefin nanocomposites. (C) 2018 Elsevier Ltd. All rights reserved.