Abstract: The composites of PA6 filled with Al_2O_3 nanoparticles were prepared by extrusion of the mixed polymeric matrix and the nano particulates on a twin-screw rod machine and injection molding of the extruded granules. The friction and wear properties of the resulting polyamide-6 composites with different contents of nanocrystalline Al_2O_3 sliding against 45~# steel in dry ambient conditions were evaluated on an MMW-1 friction and wear tester. The worn surfaces of the composites were observed on a scanning electron microscope. It was found that the incorporation of the Al_2O_3 nanoparticles in PA6 contributed to greatly reducing the wear mass loss of PA6. The PA6 composite containing 10% Al_2O_3 nanoparticles showed the best friction-reducing and antiwear behavior, which was related to the stronger interfacial bonding between the nano-filler and the polymeric matrix in this case. Moreover, the differences in the tribological behaviors of the composites with different compositions were closely related to the differences in the corresponding worn surface morphologies. It was imperative to keep a relatively lower filler content in the filled PA6 composite so as to get rid of the severe scratch to the counterpart steel surface.