Abstract: The nano-cutting process of a single crystal nickel tip into single crystal copper was studied by using quasicontinuum (QC) method. The changes of energy evolution, the stress field and atomic displacement during the cutting process were investigated. The mechanism of the chip formation was numerically revealed by combining the plastic behavior of dislocation slip with the theory of atom radial distribution. The simulated results showed that the chip formation phenomenon was resulted from the amorphization of the processed surfaces and bulk. The simulated results of different stages during nano-cutting process indicated that the nucleation and propagation of the chip shear zone occurred at the initial stage. The second stage was the formation of the metamorphic layer, which constructed the microstructure of the processed surfaces. When the transform energy stored in the crystal lattices exceeded a critical value, the crystal attics were broken. At that time, the amorphous structures were formed and considered as the last stage