The study of the effective electrical properties of reservoir rocks can be used to determine the distribution of underground oil and gas storage and identify the oil and water layers. The accurate evaluation of the effective electrical properties of rock models by digital means is of great significance not only forthe theoretical rock physics but also for the development of experimental methods and the application of electrical logging methods. As a new core analysis method, digital rock core technology has gradually become one of the effective methods for studying the effective electrical properties of rocks. Based on the technology of digital core and electromagnetic simulation, the data processing for sample image dataset, the authors carried out the numerical 3D rock model transformation and the computation of the effective electrical properties systematically. Furthermore, four types of rock samples such as sandstone and shale were investigated to discuss the validity and accuracy of the numerical core analysis method. This set of methods for data processing, numerical model conversion and calculation of electromagnetic parameters for scanned core images can be used to efficiently and accurately analyze different types of digital core dielectric constant, conductivity and other properties, which can provide important reference for such fields as rock physics, logging interpretation and reservoir evaluation.