Abstract: A high-power electromagnetic pulse transmitting device for use in a downhole, the device including a ground instrument and a downhole instrument. The ground instrument, with an industrial control computer as the core, includes a depth/magnetic mark/GPS signal recording module, a Manchester coding and decoding module, and a cable drive module, wherein the depth/magnetic mark recording and the Manchester coding and decoding modules communicate respectively through two serial ports with the industrial control computer, and the cable drive module communication for the downhole instrument through four cables by means of phantom power supply. The downhole instrument includes, in turn, from front to rear: an AC voltage boosting module, a rectifier, an energy storage capacitor, a transmitting coil, and a data acquisition module, and further includes a high-voltage discharge switch and a computer-manipulated controller. Power supply of the downhole instrument is provided by the ground instrument through cables.