Targeting the polishing of micro - sized, high aspect - ratio internal flow channel components manufactured by additive manufacturing, this particular polishing method adopts a purely physical approach, thus ensuring no chemical contamination whatsoever. It successfully compensates for the accessibility limitations of traditional polishing techniques and attains a surface quality comparable to that obtained by conventional grinding and polishing means. By effectively resolving issues such as overly rough internal cavities, residual powder, adhered slag, and the shedding of unmelted particles in 3D - printed parts, it remarkably improves the surface smoothness of the inner cavities, reduces flow resistance, and minimizes the risk of foreign object presence. Consequently, it is highly suitable for a broad spectrum of fluid - power components.