After the analysis of a large number of pigment samples, which were collected from the murals of Tang Dynasty at Mogao Grottoes, the conclusion was drawn. And by comparing those pigment samples,which were collected from the wall-paintings of earlier period of Mogao Grottoes and Kyzil Grottoes, the feature of the pigments and the rule that was obey in Tang Dynasty at Mogao Grottoes were concerned by this paper. Meanwhile, through a great quantity tests, the stability of the pigments of the murals at Mogao Grottoes were probed into, particularly the mechanism of the discoloration of red lead. Additionally, the problem was discussed that how to preventing the pigments of the wall-paintings from changing color.
