Using a combination of experimental research and numerical simulation, the effects of coarse aggregate content, interface area, and porosity on the permeability of chloridion in concrete were studied from a mesoscopic perspective.Firstly, through the RCM chloridion diffusion coefficient rapid determination test and mercury injection test, the relationship between different coarse aggregate content, water-binder ratio, porosity and chloride ionization diffusion coefficient was analyzed; then a program was established to build a concrete meso-random random aggregate model. Furthermore, the numerical simulation of chloridion diffusion performance was conducted, and the effects of meso-parameters such as coarse aggregate content and interface area on the permeation and diffusion of chloridion were analyzed.The results show that the numerical simulation is in good agreement with the test results, verifying the validity of the meso-scale numerical model; the chloridion diffusion coefficient decreases with increasing coarse aggregate content; the concrete porosity increases with increasing water-binder ratio, and further Increase the permeability of concrete; the permeability of concrete increases with the thickness of the interface zone and the diffusion coefficient of the interface zone.