Micro EDM has the ability to drill high aspect ratio micro holes in metallic materials. With the increasing of depth of micro holes drilled by micro EDM

abnormal discharges appears frequently because machining debris and gaseous bubbles cannot be effectively removed from hole. Therefore

the aspect ratio of micro hole is limited. While the planetary movement of electrode can increase the aspect ratio of micro hole duo to improving machining debris removal ability. The impact factors of the planetary movement parameters and electrical parameters on the aspect ratio of micro hole are studied

Experimental results indicate that the aspect ratio of micro hole increases along with the increase of eccentric radius and capacitor under different machining conditions. The planetary movement speed is irrelevant to the aspect ratio of micro hole. These results are helpful for actual production to improve the aspect ratio of micro hole.