Abstract: High density resistivity tomography imaging technique was used to detect fluctuant change of Quaternary bottom interface in the northern 4th mining area based on the geologic survey of Shenjian coal mine in Caiyuan. "Two Zone" was determined applying calculation numerical analysis, and the upper mining limit of 3 coal seam was finally determined by using television imager to measure the height of caving zone and water flowing fractured zone of adjacent 4 layers in mining area.