Abstract: A direct measurement device for underground coal seam permeability was developed independently; the device can directly determine the permeability of underground coal seam. The equipment and auxiliary equipment mainly include: sealing device and gas guiding pipeline, air charging device, coal seam permeability measurement device and guide pipe assembly, etc. The equipment was calibrated and verified by the State Key Laboratory of Coal Mine Disaster Dynamics and Control in Chongqing University, and the coal seam permeability of Macun Mine was measured by using the device. The results proved that the device can directly determine the permeability of coal seam underground, avoid the distortion of the laboratory measurement results caused by the accidental sampling and the destruction of the sample core, the field test results were accurate and objective.