During the process of gestation and development of rock mass instability disasters, new cracks or old cracks will develop inside the rock mass. With the development of cracks in the rock mass, the apparent resistivity of the rock mass changes continuously. It is especially important to explore the pore structure of coal rock and measure the resistivity of coal rock. But the factors affecting the electrical resistivity of coal samples are diverse, physical It is difficult to demonstrate the conductive mechanism of the coal sample. In this paper, the resistivity of coal rock is studied from the two aspects of physical experiment and numerical simulation. The error of resistivity of the two methods is compared, and the relationship between resistivity and porosity is explored. The first part of this paper is based on the actual two-dimensional core section, using artificial threshold segmentation Binary segmentation of pores and skeletons is performed on two-dimensional core sections. The construction of the digital core model needs to be based on the geometric features of the original core pore space. Based on the spatial distribution characteristics of the actual core pores, a three-dimensional digital core model was established by simulated annealing. X-ray c The instrument was scanned and 1000 two-dimensional slices were obtained, and the coal pillar model was combined and recombined. The second part uses the digital core and coal pillar model to calculate the resistivity of the finite element with comsol and matlab respectively, and can obtain the correlation between the numerical simulation resistivity and the actual measured resistivity. with The relationship between porosity and resistivity can be obtained. As the core compacts, the porosity decreases, the conductivity increases, and the resistivity decreases.