Abstract: In view of the traditional mine transient electromagnetic instrument is easy affected by the underground human interference factors, a kind of mine in-hole transient electromagnetic instrument is designed. The transmitting part of the instrument is mainly composed of bridge circuit and hidden circuit. In order to shorten the turn-off time, the voltage regulator diode between the source and gate and the absorption and blank-elimination circuit on both sides of the transmitting coil constitute a fast turn-off circuit system, which quickly release the energy in the transmitting coil and weaken the inductance effect. The receiver part has the ability of full space signal acquisition, and the dynamic range of the device meets the needs by self-adjusting the gain multiple of the secondary field signal. The test show that the instrument have the ability to probe drilling radial water cut abnormal body, because the device is located in the hole, close to target body, easy to obtain high signal-to-noise ratio of the secondary field signal, and avoid the influence of human interference factors of roadway.