Abstract: The macromolecular structure of coal was mainly affected by the metamorphism and deformation degree, the macromolecular structure was different at different deformation properties and deformation degree even though at the same metamorphism degree. In this paper, it carried out X-ray diffraction(XRD) experimental study for 17 brittle deformed coal samples with different metamorphism and deformation degree. The results indicated that the diffraction peaks became more acute, and the diffraction angle gradually increased with the increase of metamorphism and deformation degree. The values of L_c and N_c increased with metamorphism degree increasing and the deformation degree of strong brittle deformation coal was bigger than weak brittle deformation coal. The value of L_a increased with metamorphism degree increasing, but strong brittle deformation coal was obviously bigger than weak brittle deformation coal after middle and high metamorphism stage. The value of L_a/L_c first decreased and then increased with metamorphism degree increasing.