The mineral composition and microstructure of shale have an important influence on the generation and expansion in hydraulic fracturing. The shale microphysical model was established with the differential equivalent modulus model. In order to study the influence of shale mineral composition on the crack propagation caused by hydraulic fracturing, the numerical simulation analysis by the extended finite element method was carried out. The results show that the crack begins to expand when it encounters quartz, and the width and pore pressure of the crack in quartz are larger than that of pyrite. It is also concluded that quartz is more conducive to the crack propagation in the shale. In the development of shale gas, the shale layer with high quartz content would be favorable.