Tribological behaviors of Al2O3/SiC nanocomposites were found to be related to the amount of nanosized SiC and initial Hertzian contact stress. As the applied load increased, the wear volumes of Al2O3/SiC nanocomposites slightly increased, but that of monolithic Al2O3 increased rapidly above 50 N. Tribological behavior of monolithic Al2O3 was transited from mild wear to severe wear.