Abstract: For the understanding of the material removal mechanisms at the atomic level in mechanical lapping process of diamond cutting tool, molecular dynamics(MD) method was employed to establish an atomic model of diamond scratching by rigid diamond abrasive. The process of material removal and the effects of scratching depths on the cutting force and the atomic removal rate of carbon were investigated by MD simulations. Simulation results indicate that amorphization will occur in the local area of processed surface during the mechanical scratching process. The deformation caused by scratching includes elastic deformation and plastic deformation. The cutting force increases with the increase of cutting depth, and the tangential cutting force is the main factor affecting the material removal. By comparing the lattice structure identification diagram with the stress distribution diagram, it is found that the lattice failure is mainly caused by hydrostatic pressure above 100 GPa.