Organic matter and brittle minerals in "sweet spot" shale play an important role in controlling the development of fractures as well as revealing and grasping the mechanism and law related to fracture initiation, development and evolution, and hence they have a very important engineering practice value for the optimization of fractured intervals and the stimulation and stable production of shale gas. Taking Longmaxi Formation shale in northwest Guizhou as an example, the authors analyzed the mechanism of fracture control related to organic matter and brittle minerals in the "sweet spot" layer, and demonstrated a complete process of fracture formation and evolution in the "sweet spot" layer by numerical simulation experiment. The results show that the synchronous enrichment of organic matter and brittle minerals provides an important material basis for the development and evolution of fractures. The fracture tends to propagate along the structural plane formed by organic matter, and the pore structure of organic matter has obvious inducing mechanism for the formation of the fracture. Under the action of external force, the internal accumulated energy is transformed into the deformation and displacement of brittle minerals. The higher the content of brittle minerals, the stronger the fracture development capability and the higher the fracture development degree. The numerical simulation shows a whole process of fracture initiation and evolution due to the stress concentration at the end of organic pores and brittle minerals. This paper is expected to provide some references for further understanding of fracture mechanism and adjustment of fracturing parameters in the process of fracturing construction.