The performance of monocrystalline particles micro cutting has direct influence on surface finish quality. So the study angle is regularity of material removal and energy change in surface formation mechanism of monocrystalline particles micro cutting. A three dimensional model of molecular dynamics is employed to study the monocrystalline copper micro cutting mechanism. The model include the utilization of the EAM potential function,Morse potential function,and tersoff potential function to simulate the interatomic force between copper atoms,the workpiece and copper particles. The effect of particles cutting direction and velocity and ensemble temperature on particles micro cutting in nano scale with the model are analyzed. Through discussing the effect of system kinetic energy and potential energy and total energy on workpiece-atomic movement rule,and the change of bond angle with particles micro cutting,it provides theoretical basis for surface formation mechanism of monocrystalline particles micro cutting. The results show that the surface finish is better in orthogonal cutting than that in bevel cutting,linear relationship of particles velocity and energy don’t exist and particles temperature have direct influences on system energy. Molecular dynamics simulation is carried out to get system structural information and thermodynamic property and provides a method to search appropriate machining parameter. Through the simulation,the technical support for the study on particles micro cutting processing technology is provided.