Abstract: The traditional digital core technology has some limitations in the process of establishing three-dimensional model, which leads to the poor accuracy of numerical simulation test analysis. In order to optimize the modeling technology, CT scanning +MATLAB image processing +AVIZO 3D reconstruction method improves the traditional modeling method, and relies on ABAQUS numerical simulation software to establish a 3D digital core model. The physical and mechanical parameters of digital core were compared with those of laboratory tests, and a microunit digital core model was constructed to explore the damage evolution law during uniaxial stress loading. The results show that the established 3D digital core model can capture the stress-strain curve characteristics of laboratory test well, and has the same crack propagation mode. The distribution of multiple media in the microcell digital core model greatly affects the evolution of stress and damage in the core. Among them, the development of tensile damage lags behind that of compression damage, and the tensile damage region is also significantly lower, with a difference of about 74 times in the postpeak region.