Abstract: The permeability and mechanical deformation tests were conducted by the self-developed triaxial stress seepage experiment system under different stress levels, and the characteristics of permeability variation and mechanical deformation in coal samples fatigue failure process were studied on the response of stress level. The test results shown that:The hysteresis loops of the stress-strain curves shows the three stage characteristics of sparse-dense-sparse, and with the increase of horizontal stress, the cycle times are greatly reduced and the hysteresis loop is less;with the increase of cycle numbers, the permeability showed three stages of reduce-stability-rising, the whole curve present “U” type, and with the increase of stress level, the curve has the trend of "V" type. The mechanical deformation and permeability changes have close relationship in coal samples, in the process of circulation, the change tendency of the coal samples in permeability and strain accumulation volume growth were the same, which experienced the process of slowdown - stability - accelerate.