Abstract: the experiments of coals with different ranks under high temperature and high pressure had been showed that under the action of high temperature and high pressure and differential stress,the reflectance values and anisotropies of coal vitrinites all increased in a certain degree The more violent the coal deformed,the more they increased,especially in the middle and stages of the middle rank coals In the deformation processes of the coals,the principal axes would rotated regularly The minimum principal axes of vitrinite reflectances were gradually closed to the directions of the maximum compression stresses The ellipsoids of the vitrinite reflectances were changed from the pattern of unidirectional extension to the one of unidirectional compression.