The pulse duration of discharge current greatly influences the removal amount of anode and cathode in EDM process. The purpose of this research is to find out the reason for such a phenomenon. At first, the energy distributed into anode and cathode in the case of the single discharge process is obtained by means of measuring the temperature rise and removal amount of electrodes. Then the influence of the carbon adhesion onto the anode surface on the anode removal amount is investigated. It is found that the energy distributed into the anode is more than that into the cathode, and the influence of pulse duration on the energy distribution is small. Besides, it is concluded from the experimental results that the removal amount difference between anode and cathode in the EDM process is mainly caused by carbon adhesion, not by the energy distribution.