Hydrothermal treatment of silicon aluminum zeolites is a common modification method in the field of industrial catalysis. More and more experimental evidence has been obtained for the research on the changes of zeolites structure during hydrothermal treatment and catalytic performance, including dealumination mechanism, the existence form of extra-framework aluminum species and the synergistic mechanism of extra-framework aluminum in catalytic reaction[1-2]. Because of its particular structure, mordenite zeolites are widely used in industrial reactions such as hydrocarbon isomerization and alkylation of polycyclic aromatic hydrocarbons. Through further post-treatment of mordenite zeolites, the distribution of aluminum species and pore environment can be adjusted, and better catalytic performance can be obtained in some reactions. Solid state NMR is a powerful tool to investigate the structure of zeolites. In addition to the direct determination of framework elements such as silicon and aluminum, the information of acidity and pore structure can also be obtained indirectly through the characterization of probe molecules. How to realize the designed modification of zeolites structure in hydrothermal treatment process, especially combined with subsequent acid treatment and other steps to obtain rationally designed catalyst products, has always been the focus of industry. In this paper, the fine structure characterization of mordenite zeolites under different hydrothermal treatment conditions, such as temperature and duration, was studied by kinds of solid-state NMR experiments. The evolution process of aluminum species and the change of chemical properties under different treatment conditions were investigated, thus the adjustable acidity of mordenite zeolites can be realized. The structure-activity relationship of various species was further investigated by model reaction, which provided important experimental evidence for the improvement of industrial catalysts.