Abstract: Because the three dimensional geostress in crustal rockmass exists often in the pattern of compressive stress, the weak layerzone in rockmass bears normal compressive stress caused by the three dimensional geostress (natural confining pressure). In this paper, the authors study the engineering properties (physical mechanical properties) of argillaceous material in weak layerzone under the naturally confining pressure, and fine the well correlation between the engineering properties of argillaceous material at the condition of natural compression and its natural confining pressure, and then point out the existing problems in present studies on engineering properties of weak layerzone in neglecting natural geostress.