Microstructures and mechanical properties of Al–Cu matrix composites reinforced by in situ TiB 2 and Al 2 O 3 particulates have been investigated in this paper. Result of XRD analysis indicates that the (Al 2 O 3 +TiB 2 )/Al–Cu composites can be fabricated with the direct melt reaction method. Analysis in SEM shows that TiB 2 particles distribute along the grain boundaries and interweave with CuAl 2 phase; while Al 2 O 3 particles have a tendency to agglomeration. The interfaces between reinforcements and matrix in as-cast composites are clean. From the investigations on mechanical properties of composites, we deduce that the UTS and hardness of as-cast or T6-treated (TiB 2 +Al 2 O 3 )/Al–Cu composites are obviously higher than those of composites reinforced with the same percentage reinforcements of TiB 2 or Al 2 O 3 particles.