The work aims to improve contact behavior of micro/nano devices. Allowing for influences of adhesive force, elastic-plastic deformation of single crystal copper substrate, and neglecting anisotropy, adhesion contact and separation process of probe and single crystal copper was simulated dynamically, contact force during contact and separation process was analyzed in molecular dynamics method based on mixed potential function (EAM and Morse) and Verlet algorithms. Atomic destruction and migration path changes in contact area were analyzed based on center-symmetric parameters. During pushing contact processes, slip bands successively appeared on both sides of the contact area and gradually expanded in both directions as contact force increased. Besides, angle between slip band and probe pressing direction was 45?. After separation, under the effects of elastic-plastic recovery and energy dissipation of substrate, slip zone on either side of slip band first expanded and then gradually narrowed. After complete separation, atoms on copper substrate stuck to the surface of probe bottom, "shrink neck" and hysteretic displacement, as well as adhesion delay were obviously observed between the probe and substrate, which were the main cause of adhesion failure on contact surface. What’s more, lattice atoms in contact area fractured and accumulated in "V" shape during the whole contact and separation process. The adhesion influence makes atoms on substrate stick to the probe bottom surface, leading to adhesion delay, which is the main reason of adhesion failure on micro-nano machinery.