Based on the previous research, this paper establishes the relationship between the dewatering transformation of the clay minerals and the diagenetic stages and the formation of pore fractures. The influence of temperature, time, pressure, pore fluid properties and thermal evolution of organic matter on the transformation of clay minerals is summarized. By comparing the paleogeotemperature in the transformation of various clay minerals and change of fluid properties, the diagenesis evolution of shale is divided into three stages, and the difference of main diagenetic reaction in each stage leads to the variance of mineral assemblage.The adsorption capacity of methane is closely related to the transformation of clay minerals in shale diagenesis.The experimental results show that the order is smectite>illite/smectite mixedlayer>kaolinite>chlorite>illite. Illitization of smectite and chloritization of smectite are important diagenetic reactions, and the study and establishment of their genetic mechanism model have a certain reference significance for the study of shale reservoir.