With the continuous development of conventional oil and gas resources, its stock resources are becoming less and less. The successful development of unconventional oil and gas resources in the United States has laid the technical foundation for shale gas exploration and development. Reservoir reconstruction technology is one of the two key technologies to determine the success or failure of shale gas development. The brittleness index of shale gas reservoirs is a key indicator for evaluating the shale gas reservoirs that can be modified (fracturable). In this paper, extensive and in-depth research on shale gas reservoir brittleness evaluation methods at home and abroad is carried out, and various mechanical characterization methods of rock brittleness and the influence of mineral composition on rock brittleness are summarized. That provides basic reference materials for the study of shale gas reservoir brittleness evaluation methods in China.