Abstract: Using Fourier infrared spectra and X-ray diffraction, in this paper the difference of chemical structure of two types of vitrinite with different reductivity and their change regularities according to coal rank in the southern part of North China are studied. The vitrinite with stronger reductivity had more aliphatic structure and less aromatic structure than those of the vitrinite with weaker reductivity. The evolution of structure in vitrinite involved with the crystallizing degree of aromatic structure increased. Some parameters of chemical structure in vitrinite, such as aromaticity, foe distance between surface network, the height and width of crytal nuclear, and the number of aromatic ring varied regularily with coal rank increased.