Abstract: In order to study the effect of porosity and dynamic loading on gas permeability of tectonic raw coal specimen under negative pressure drainage, a gas-solid coupling triaxial stress servo seepage experimental device was developed. Experimental results show that the porosity has more significant influence on gas permeability of raw coal; the gas permeability increases with the increasing of porosity; under the constant condition of confining pressure, drainage negative pressure and gas inlet gas pressure, the permeability increases slightly with the increasing of the axial compression; after reaching the peak point, it decreases rapidly with the increasing of axial pressure; the gas permeability increased slowly during the axial pressure unloading process, however, it is difficult to restore to the initial permeability; under the condition of maintaining the same confining pressure, axial pressure and gas pressure, permeability increases with the increasing of negative pressure, this effect has little influence under high stress.