Abstract: The transient electromagnetic method is widely applied to the coal mine hydrogeological exploration and other fields because of being sensitive to low resistivity body, convenient operation and so on, but applied little goaf water exploration made. In this paper, the transient electromagnetic method over the years in the coal mine hydrogeological exploration has got exploration experience, through in-depth study of OCCAM inversion technique, application of the inversion method of the detection data, in a coal mine in Yanchi County, Ningxia Hui Autonomous Region successfully detected the gob water position and the distribution range, which was verified by the later drilling, exploration results provide a powerful basis and basic data for the construction of the drainage system and comprehensive water prevention and control system. Note:use the instantaneous electromagnetic method to detect gob water, select effective inversion method, can achieve better prospecting effect in shallow, medium depth region.