In order to obtain the deformation characteristics and permeability variation law of low rank coal, the original sample of 3# coal in Xiashijie coal mine in Jiaoping mining area was taken as the research object, the coal deformation and seepage experiments were carried out under the conditions of effective stress, matrix shrinkage and their comprehensive effects by using the multi-process coupling test system of stress-seepage-temperature of coal and rock mass. The results show that in the process of increasing effective stress, the negative volumetric strain of coal increases gradually, the coal shrinkage and permeability decrease gradually; in the process of matrix contraction, with the gradual decrease of pore pressure, the negative volumetric strain of coal increases gradually, and the shrinkage of coal body and permeability increases gradually; under the combined action of the two factors, with the gradual decrease of pore pressure, the negative volume strain of coal body gradually increases, the coal shrinks, and the permeability first decreases and then increases. By comparing with the typical permeability dynamic change model under the condition of equal external forces, the Lu model is more consistent with the experimental data. The experimental results are helpful to predict the dynamic change of coal permeability and guide the development of surface coalbed methane and the prevention and control of coal mine gas.