In the previous paper, concrete was considered as a three phase composite material consisting of aggregates, interfacial transition zone and mortar, and the random delivery model of concrete aggregate was established by MATLAB software. The model was introduced into COMSOL software, and the effect of different aggregate content and volume of interfacial transition zone on chloride ions diffusion was investigated. By means of design of experiment, the repeatability of the proposed model was verified and simulation precision was confirmed. The effectiveness of the model was tested by the comparative analysis of experimental data and simulated results. The simulation results show that the diffusion of chloride ions is restrained with increase of aggregate content, which is manifested by zigzag effect of the aggregate; the chloride ions diffusion is accelerated with volume of interfacial transition zone increase, which is assumed as interface effect. With the increase of aggregate content, the interface effect becomes more and more obvious.