In the consideration of the non-uniformity of composites, the classical single-shear-plane metal cutting mode and shear angle equations are thought to be unsuitable for analyzing the cutting process of SiC-particles-reinforced aluminum matrix composites, but no ideal cutting mode has been established on the basis of pure analytical mechanics for this kind of material so far. Experiments have indicated that the chip deformation coefficient of SiC-particle-reinforced composites decreases and the shear angle increases in comparison with those for the normal matrix aluminum alloy. There is an obvious difference between the two cutting processes of coarse-particles-reinforced composites and fine-particles-reinforced composites: in the latter, continuous chips predominantly form, and in the former, not only continuous chips, but also debris, are found. Both cutting process modes are considered in this paper.