Insulating ceramics are applied to modern manufacturing industries for their improved material properties.But they are the difficult-to-machine materials because of their high rigidity,high brittleness and non-electrical conductivity.A new method which employs a high energy capacitor for electric discharge machining of insulating ceramics efficiently is presented in this paper,and the single discharge experiments have been carried out.The process uses the high voltage,large capacitor and high discharge energy,it is able to effectively machine insulating ceramics,and the single discharge crater volume of insulating ceramics can reach 17.63 mm3.The effects of polarity,peak voltage,capacitance,current-limiting resistance,tool electrode feed,tool electrode section area and assisting electrode thickness on the process performance such as the single discharge crater volume,the tool wear ratio and the assisting electrode wear ratio have been investigated.The microstructure of the discharge crater is examined with a scanning electron microscope(SEM).The results show that the discharge craters have sputtering appearance,the insulating ceramic materials are mostly removed by spalling,in the center region of the discharge some materials are removed by melting and vaporization,and the material removal is enhanced with the machining parameters increasing. Insulating ceramics are applied to modern manufacturing industries for their improved material properties. But they are the difficult-to-machine materials because of their high rigidity, high brittleness and non-electrical conductivity. A new method that employs a high energy capacitor for electric discharge machining of insulating ceramics efficiently is presented in this paper, and the single discharge experiments have been carried out. The process uses the high voltage, large capacitor and high discharge energy, it is able to effectively machine insulating ceramics, and the single discharge crater volume of insulating ceramics can reach 17.63 mm3. The effects of polarity, peak voltage, capacitance, current-limiting resistance, tool electrode feed, tool electrode section area and assisting electrode thickness on the process performance such as the single discharge crater volume, the tool wear ratio and the assisting electrode wear ratio have been investigated. The microstructure of the discharge cr the results show that the discharge craters have sputtering appearance, the insulating ceramic materials are mostly removed by spalling, in the center region of the discharge some materials are removed by melting and vaporization, and the material removal is enhanced with the machining parameters increasing.