SiC ceramics have been widely used in a variety of areas due to the excellent physical and chemical properties. However, the process of SiC ceramics is difficult and high-cost, molecular simulation is an effective and feasible method to study the nano-process of SiC ceramics. In this paper, a molecular model is presented to simulate the stress and energy in the nano-cutting of SiC ceramics. The influences of the cutting depth and cutting speed on the kinetic energy and potential are analyzed. The results show that potential energy increases with the decrease of the cutting depth. Kinetic energy increases with the increase of the cutting speed. The results are very helpful for improvement the level of ultra-precision processing and nano-processing of brittle ceramics.