This paper has analyzed the particularity of the geophysical field in the coal mine. It is indicated that measuring resistivity in frequencydomain has advantages of suppressing the industrial noise in an effective way and overcoming the bad earth condition of the ground electrodes. In addition, it meets the requirement of the underground work. The application of this method in a coal mine shows that it can accurately locate the anomalous body in threedimensional space. It can therefore be used to detect the waterbearing and waterconducting structures in a coal mine before the beginning of the mining work.