Chloride concentration profiles of concrete specimens with port engineering and their corresponding mortar specimens are measured and obtained during the in-site field exposed experiment,and the chloride diffusion coefficients of these two types specimens are determined by regression analysis.On the basis of the two chloride diffusion coefficients,the influences of dilution,tortuosity and interfacial transition zone effects on chloride diffusion coefficient of concrete are quantified,as well as the chloride diffusion coefficient model of interfacial transition zone of concrete is established.The accuracy of the aforementioned model is validated based on the meso-scopic numerical simulation method of chloride diffusion into concrete.Based on the analysis of the mesoscopic numerical simulation results,it can be seen that the enhancement effect of interface transition zone on chloride diffusion coefficient in concrete considering only the dilution and zigzag effects of coarse aggregate cannot be ignored.The influence of the interfacial transition zone on the chloride concentration distribution and diffusion characteristics in concrete should be considered.