This paper deals with the electron beam drilling of alumina green sheet. The following results were obtained through some experiments by multi-pulse drilling under various duty factors and a thermal calculation. (1) The number of beam pulse does not affect the diameter and taper of drilled hole. Furthermore, hole taper is kept constant for various value of workpiece thickness when drilling are performed in same conditions. (2) Hole diameter and taper increase dramatically at high duty factor even though drilling conditions are kept constant. (3) Material removal in the drilling of green sheet is taken place through scattering of surrounding material by explosive vaporization of organic binding material in the green sheet. (4) The increase in hole diameter and taper is due to the focal movement taken place through the space charge neutralization by positive ions generated by the ionization of vaporized gas.