Pure Al powders were mixed with a 30 % volume fraction of Al2O3 powders having particle sizes of similar to 30 nm. The mixed powders were first subjected to ball milling (BM) and thereafter consolidated by high-pressure torsion (HPT) at room temperature under a pressure of 3 GPa for 10 turns. The Al-Al2O3 composite produced by BM and HPT (BM + HPT) had a more uniform dispersion of the nano-sized Al2O3 particles in the Al matrix. Hardness values of the BM + HPT composites were higher than those of the composites without BM. It is shown that the use of BM powders for HPT is more effective in achieving a uniform dispersion of the nano-sized Al2O3 particles and in improving mechanical properties of the Al-Al2O3 nanocomposites.