To overcome the disadvantages generated by the loosened nanoparticle agglomerates dispersed in polymer composites, a chemical grafting method was applied to modify nano-alumina, silicon carbide and silicon nitride through covalently introducing polyacrylamide (PAAM) onto the particles. Sliding wear tests demonstrated that the frictional coefficient and specific wear rate of the nanoparticles/epoxy composites are lower than those of unfilled epoxy. Grafted nanoparticles reinforced composites have the lowest frictional property and the highest wear resistance due to the strengthening of the nanoparticle agglomerates and the enhancement of filler/matrix interfacial interaction resulting from the grafting polymers. Comparatively, graft treatment of nanoparticles is more beneficial to the improvement of the tribological features of the composites than the silane treatment that is used conventionally.