Abstract：Metamorphism and deformation of coal not only have an important impact on its macroscopic characteristics, but also affect its microcrystalline structure. The microcrystalline structure of coal is one of the intrinsic factors that affect the physical properties of coal reservoir. In order to study the evolution characteristics of microcrystalline structure of different metamorphic and deformed coal, X-ray diffraction ( XRD) was used for studying the microcrystalline structure parameters of different metamorphic and deformed coals in the whole coal ranks. The results showed that, with the increase of coal rank, interplanar distance d002 decreased gradually, stacking height Lcand aromatic layer mumber Ncincreased gradually, which showed a certain stage, and the values of above parameters tended to be stable eventually. The relationship between Laand Ro, maxwas linear, and the value increased with the increase of coal rank. Tectonic deformation of coal lengthened the variation range of microcrystalline parameters of coal, and made coal microcrystalline structure evolved ahead of time in the basis of metamorphism. The tectonic deformation of coal had a positive effect on the increase of Lc, Laand Nc. The weak tectonic deformation had little effect on the final stability value of d002, and the final stability value of d002 for strong tectonic coal was smaller than that of raw coal. The microcrystalline parameters of raw coal, the weak and strong tectonic coal had different characteristics with the changed of coal rank. The microcrystalline parameters for the tectonic deformed coal change more widely than that of raw coal.

Keyword：raw structural coal;weak tectonic deformed coal;strong tectonic deformed coal;X-ray;maximun reflectivity;