Micro hole with high-aspect-ratio is widely used in key parts of core equipments in fields of aerospace industry, energy power, carrying and medical appliance. Because diameter is small, aspect ratio is high and part materials are difficult to machine, the efficient and steady machining of the hole is quite difficult. EDM (electrical discharge machining) become a machining method of high-aspect-ratio micro hole since it does not has macroscopic force, is not influenced by material mechanical properti...