Abstract：According to the similitude material model test，the new measurement system about the coal rocks penetrability coefficient on the similitude material model has been designed. The change of the protected coal seam penetrability was measured，and the protected stratum penetrability change laws in time and space were studied during the far-distance protecting stratum mining firstly. The results indicate that the penetrability coefficient of the protected stratum was a dynamic change and according to “M”. The found conclusions were in accordance with the measured in coal mine. The scientific foundation has been got for the reasonably arranging preventing coal seam and unloading pressure drawing gas in the low penetrability high gas content coal seam.
