Baikouquan formation in Mahu sag, Junggar basin is one of the main development strata of 1 billion ton super large Mahu conglomerate oilfield. It belongs to a typical low porosity, low permeability ultra-low permeability reservoir. It needs to form a large-scale complex fracture network through volumetric fracturing to achieve efficient development. The brittleness of conglomerate formation is the key mechanical index of fracturing to form a complex fracture network. A large number of studies on rock brittleness mainly focus on shale formation, for the complex and strongly heterogeneous conglomerate, the brittleness characteristics need to be deeply and systematically studied. Focusing on the brittleness characteristics, evaluation methods and influencing factors of the conglomerate of Baikouquan formation, through the rock physics and rock mechanics experiments of conglomerate coring and the analysis of rock sample deformation and failure characteristics, it is clear that the conglomerate of Baikouquan formation presents low brittleness or plasticity under the condition of formation confining pressure; Based on the calculation and comparison of different brittleness indexes, combined with the brittleness characteristics presented in the experiment, it is clear that the brittleness index based on secant modulus can better characterize the brittleness characteristics of conglomerate in Baikouquan formation; The brittleness index of conglomerate is closely related to confining pressure, porosity and density. With the increase of confining pressure and porosity, the brittleness of conglomerate decreases and the plasticity increases; With the increase of density, the brittleness of conglomerate increases and the plasticity decreases. The research and understanding is of great significance to the optimization of “sweet spot” and fracturing engineering design.