Abstract: As an important part of roadway surrounding rock, the meso-damage characteristics of sandstone directly affect the stability of roadway surrounding rock. The mineral crystal structure of sandstone with different particle sizes has obvious heterogeneity. In order to study the mesoscopic law of sandstone crack evolution, the methods of laboratory test, numerical simulation and theoretical analysis are comprehensively used to study the three different particle sizes of sandstone specimens drilled from the roadway surrounding rock. A two-dimensional equivalent crystal Model Grain-Based Model（GBM） is constructed based on PFC^2D software to analyze the crack evolution law of heterogeneous sandstone specimen during fracture process is analyzed from the microscopic point of view. The results show that the smaller the particle size of the sandstone specimen, the more the total contact number of the rock and the smaller the proportion of the intergranular contact in the total contact, the more acoustic emission signals generated by the rock and the more cracks generated inside the crack during uniaxial loading, the greater the uniaxial compressive strength of the rock specimen and the more severe the failure mode. The crack evolution laws of the three sandstone specimens with different particle sizes is consistent. In the uniaxial loading process, the internal crack evolution sequence of the sandstone is intergranular tensile crack, intracrystalline tensile crack, intergranular shear crack, and intracrystalline shear crack. The number of cracks generated in sandstone mineral crystals is proportional to the mineral content and inversely proportional to the strength of mineral crystals. The number of cracks per unit area coefficient K_l is defined, and the mineral strength is inversely proportional to K_l. Tensile cracks account for more than 90% of the total cracks when sandstone samples are damaged, and tensile failure is the main failure type of sandstone under uniaxial compression.