The tensile properties of 2124Al alloy composites reinforced with various sizes of SiC particles were investigated at room temperature. The size of SiCp was changed from 0.2 mum to 48.0 mum with an identical volume fraction of 20%. The results show that the relative density of the composite decreased with increase of the SiCp size from 3.0 mum to 48.0 mum, whereas 0.2 mum SiC, reinforced composite has the lowest relative density. The pore density, interparticle spacing, SiC particle cracking, SiCp/Al interfacial debonding, the distribution of SiC particles, in the composites are considered as factors to determine the failure behavior of the composites.