Abstract: The permeability experiment of hard rock and soft rock are done under triaxial compressive stress. The permeability, confining pressure, axial pressure, and water pressure are observed. These experiments indicate the permeability coefficient is inversely proportional to increasing effective stress .The permeability coefficient of soft rock is lower than that of hard rock and is more significantly affected by effective stress. The water-resisting capability of the two rocks and the mechanism for water inrush through the cracks in rock mass are analyzed according to the experiments.