Abstract: In the process of deep coal mining, due to engineering disturbances, the ground stress undergoes complex changes, which leads to changes in the mechanical properties and permeability characteristics of coal. In this paper, the fluid-solid coupling tests of coal samples under certain axial stress, different unloading pressure rate and different gas pressure conditions were carried out. The mechanical and seepage characteristics of coal samples under different stress unloading pressure rats and gas pressures were studied. The results shown that with the increase of unloading rate and gas pressure, the deformation and plasticity platform of coal samples were gradually strengthened. The deformation modulus, lateral deformation coefficient and effective confining pressure of coal samples decreased with the increase of unloading pressure and gas pressure. During the axial compression loading phase, the permeability was gradually reduced due to the compaction of the primary fractures. In the confining pressure unloading stage, the expansion of primary pore fissure caused by confining pressure unloading and the new fissure caused by high deviated stress difference lead to the increase of total fissure and permeability.