Abstract: SiCp/Al composites are widely used in various fields because they have the combined properties of both aluminium matrix and silicon carbide particles, and therefore have low density, high thermal conductivity and high hardness. However, the high hardness of brittle SiCp/Al composites makes traditional contact machining difficult due to high cutting temperatures, severe tool wear and machining accuracy. In this paper, the effect of material etching rate and electrode loss on the machining of SiCp/Al composites under different machining parameters was investigated on a self-built EDM test bench with SiCp/Al composites, and the reasons for the effect on the machining were analysed in terms of the etching characteristics of the composites.