Abstract: SiCp/Al composites with 63 % SiC in volume fraction were successfully prepared by powder injection molding and pressureless infiltration. The effects of major processing parameters on the properties of SiC preforms and SiCp/Al composites were investigated. The results showed that SiC preforms prefired at 1100 ℃ or lower temperature exhibited high open porosity, which is over 97.9 % of the whole porosity. The SiO₂ film resulting from the oxidation of SiCp at high temperature can remarkably enhance the wettability of SiCp by Al alloy liquid, leading to a significant increase in density of the composites. After optimization of the processing parameters, the SiC performs were well wetted by Al alloy liquid. As a result, an SiCp/Al composite with a higher relative density of over 97 % was obtained.