Abstract: Based on the special environment of coal caving in the thick coal seam, and considering the characteristic of the strain softening for the coal and according to the distribution regularity of the support pressure for the coal pillar in the progress of mining, calculating formulation of the coal pillar for the thick coal seam based on the coherent material SMP (Spatially Mobilized Plane,) failure criterion. In the thick coal seam of the Wangzhuang coal mine, calculating formulation is applied well, and it also consummates the theory of the narrow coal pillar stability for the thick coal seam. It has guiding significance for the narrow coal pillar mining in the condition of the thick coal seam in china.