Abstract: With the development of image recognition and pattern recognition technology, dry sorting based on ray has been widely developed and applied, especially in arid areas. When sorting coal and gangue by X-ray transmission technology, recognition of coal and gangue are based on the differences of X-ray absorption. Previous works have paid much attention to the atomic number and density. Only coal and gangue with large density difference can be identified, and the deep mechanism of identification cannot be well explained. At the same time the relationship between the evolution of crystallographic structure and X-ray absorption has not been researched. Experimental methods including TG / DSC, XRD and FTIR were used to detect the change of kaolinite during annealing. Materials Studio was used to simulate the possible crystal structure during the gradual disordering of kaolinite crystal structure. The simulated structures were calculated by FEFF9 for X-ray absorption spectroscopy. The results show that X-ray absorption fine structure spectroscopy can represent valuable information about the Si local environment in kaolinite. Further investigation determined that the XANES absorption peak shifts slightly from 1846.7 eV to 1845.1 eV and the intensity mutation increases from 1.76 to 3.86 with the increase of kaolinite distortion in stages. This work proves the study on the distortion mechanism of kaolinite crystal during annealing with FEFF9 calculation which provide theoretical support for identifying kaolinite with different distortion degrees in coal gangue separation.