Aiming at the problem of long production cycle of cooling holes in the aero-engine blades with EDM method and the poor processing quality of the ND:YAG laser drilling, one step EDM of cooling holes was proposed based on assisting method. Due to significant difference in gap discharge state between ceramic coatings and superalloys, current EDM control systems were able to achieve a stable and accurate control, which cannot make a compromise on processing efficiency and quality. Therefore, Key techniques for EDM of cooling holes were studied, including discharge state identification method of thermal barrier coated-superalloy, pulse power supply and servo control strategy based on fuzzy control. Based on the above technology, the EDM control system for drilling thermal barrier coated-superalloys was developed. The comparison experiments show that compared with the conventional EDM control system, the self-developed system can improve processing efficiency by 110%, and can obtain better machining quality.