Abstract: The physical and mechanical properties of deep buried clays differ from those of shallow buried clays due to deep burial, high pressure and long solidification time. To study the permeability of the deep buried clays', clay samples are taken from Longgu Coal Mine in Shandong Province, and their permeability is tested by using the SJ-1A.G triaxial shear equipment. Firstly, the curve which shows the relationship between coefficient of permeability and axial stress is studied, and a regression equation I was found to describe it. There are some differences of regression coefficients between deep buried clays and shallow buried clays. Secondly, the anisotropy of permeability and the internal reason of the deep buried clays are analyzed. Finally, the curve which shows the relationship between coefficient of permeability and axial strain is studied. The curve of the deep buried clays' doesn't have a segment stretched with little slope and this is because the shallow buried clays will yield under high pressure, while the deep buried clays will develop micro-crack. The study is of guiding significance for the waterproof design in thick covered mines and deep excavations