Ultraprecision metal cutting (UPMC) technology, which makes possible submicrometre form accuracy and nanometre roughness, is developed to reach the 1 nm nominal (undeformed) thickness of cut. At this thickness level, the finite element method (FEM) cannot be used to solve the problem. Molecular Dynamics can be applied to this small cutting depth. In this paper using molecular dynamics simulation, microcutting with a subnanometre chip thickness, the cutting mechanism for the microcutting condition, i.e. tool edge configuration, cut material and cutting speed, are evaluated. As the result, the simulation of the cutting mechanism at subnanometre depth of cut is evaluated.