Single-crystal tungsten is widely utilized in various fields, benefiting from its outstanding properties. Nano-cutting, as an ultra-precision machining method, can realize high efficiency and low damage. However, from the atomic perspective, the formation mechanism of subsurface damage during the nano-cutting of tungsten is still unclear. Herein, the molecular dynamics (MD) simulation of nano-cutting single-crystal tungsten was established to elucidate the evolution of subsurface damage and the effects of cutting force on subsurface damage. The corresponding results showed the existence of damage including atomic cluster, vacancy defect, “V-shaped” dislocation, stair-rod dislocation, and dislocation ring on the subsurface during the cutting. There were dislocation lines in 1/2<111>, <100>, <110>, and other directions due to plastic deformation dominated by dislocation slip, and the 1/2<111> dislocation lines could be merged into stable <100> dislocation lines under certain circumstances during the cutting. The variation of cutting force and cutting force fluctuation induced by changing cutting parameters had a great influence on the subsurface damage of tungsten, including the number of surface defect atoms, dislocation density, and thickness of the subsurface damage layer. In nano-cutting of single-crystal tungsten, a smaller cutting depth and appropriate cutting speed should be selected to reduce subsurface damage. This study provides an insight into the evolution mechanism of subsurface damage of tungsten and is high of significance for achieving low-damage machining of tungsten components.