Abstract: Using the self-designed and modified coal rock mass triaxial stress seepage experiment device, taking low permeability and soft tectonic coal as the test sample, we carry out the triaxial stress seepage experiment, and study the permeability law of soft tectonic coal under the condition of negative pressure extraction. The experiment result shows that the permeability of coal gas increases with the increase of negative pressure under the condition of constant confining pressure, axial pressure and inlet gas pressure in the process of static loading; when the negative pressure is higher, the increment of gas permeability is relatively small, and the increment of permeability is zero when the negative pressure is 30 kPa; by changing the axial pressure, confining pressure and inlet gas pressure and comparing the difference among different groups, we find that the gas permeability of tectonic coal decreases with the increase of axial pressure and confining pressure, and improving gas pressure is beneficial to the improvment of permeability, however, the permeability increases slightly in general.