Abstract: A mine-used intrinsically safe transient electromagnetic instrument based on STM32 is designed. The transmitting part suppresses the interference of power frequency and its multiple harmonics by transmitting a bipolar square wave; the receiving part uses data superposition and multiple iterations to realize the synthesis of the early, middle and late signals of the collected signals to improve the dynamic range and signal-to-noise ratio. The underground measurement shows that the receiving voltage drops from the maximum 43.528 V to 1.323 μV, and its receiving dynamic range is more than 150 dB; and compared with similar equipment, the results are consistent with the on-site roadway humanities facilities and water output conditions, which can meet the requirements of mine transient electromagnetic instrument for advance detection of underground roadway.