Abstract: The detection of micro-EDM discharge state and the accurate control of discharge gap are the important basis for ensuring high quality and high efficiency machining. Based on the characteristics of inter-pole impedance, a new detection method is proposed, and a micro-EDM discharge detection system is designed by using ADS8681 and STM32.The serial port is used to communicate with the power control module to realize detection enabling control and detection state feedback. The inter-pole discharge voltage signal is collected by SPI control ADS8681 as the state judgment basis. DAC output module is responsible for output control signal. The system can accurately identify the discharge state between poles and output differential control signal according to the processing control strategy. This system can realize the accurate identification of discharge state and the control of machining gap to ensure the high quality and high efficiency of micro-EDM.