In this paper, using the EAM potential, three-dimensional Molecular Dynamics simulations were carried out to study the effect of spherical nano-void and its size on nano-cutting parameters of copper. Then, a comparison was made with a perfect single crystal. The numerical results revealed that due to high hydrostatic pressure during nano-scale cutting, the nano-void was crumpled indicating that void inclusion in material can influence tool forces if the void diameter is bigger than the depth of cut and if it is placed near the machiningsurface. Further, the existence of spherical nano-cavity in workpiece affects the uniformity of chip formation proportional to void size. In workpiece with large void, large plastic deformation occurs in two regions: at machining surface due to chip formation and in adjacent void areas because of void crumpling. Finally, indefected workpiece with a large void diameter, the compressive stress area between machining surface and void is transformed to shear stress.