A series of copper–Al2O3 composite materials (CACMs) with 0, 2, 4, and 6 wt.% of Al2O3 (average size about 80 nm) was fabricated by powder metallurgy method. The tribological behavior of CACMs was investigated by a ring-on-block sliding friction test. The results show that the hardness and the wear resistance of CACMs are improved by the addition of Al2O3. The CACMs with 0% Al2O3 (pure copper) shows the mechanism of adhesive wear and have very poor wear resistance. By comparing with the pure copper, the wear resistance of the CACMs with 2% and 6% Al2O3 is improved. When the proportion of Al2O3 is 4%, slightly abrasive wear occurs at the interface between two sliding surfaces, and the CACMs achieve higher wear resistance in comparison to that with 2% and 6% Al2O3.