Abstract: The paper proposed a deformation-resistivity method. It is based on the realtionship between the resistivity in the undreground rodk body and its lithologic character and water content, that is the resistivity value relatively increased after the stratum relief and resistivity value relatively dicreased after filled water of the broken crack surface in the normal stratum. We survey curve according to the differences between the underlying gigantic thickness O₂ limestone and upperlying stratum elective parameter. It showed that resistivity method has a series of advantage for survey water- resisting layer thickness of the coal seam bottom and uplift height of the bottom water.