By tests,the quantitative study and analysis were made on the permeability changes of red sandstone in complete deformation and failure process under three-dimensional stress.The results shown that the shear-induced dilatancy occurred early prior to the final failure,the onset stress of dilatancy was approximate 46% of the ultimate compressive strength of the red sandstone.The permeability in the red sandstone decreased continuously with the increment of the longitudinal compressive stress,the permeability arrived at the lowest value and kept constant as soon as the peak stress was reached.The confining pressures and penetrative pressure difference has notable effects on the permeability of the red sandstone,the higher confining pressure lead to the lower decreasing velocity of the permeability,the higher penetrative pressure difference induced the lower permeability and the higher decreasing velocity of the permeability.