The relationship between wet-dry cycles and chloride diffusion coefficient was investigated by using four different concretes. Chloride diffusion coefficient was estimated by applying the model of three-dimensional diffusion with the chloride contents of the concrete at different wet-dry cycles. The result showed that there existed the positive power function relation between the chloride diffusion Coefficient of concrete (Dcx) with wet-dry cycles, the value of Dcx had a typical positive correlation with wet-dry cycles, fly ash or slag addition amount, and the content of silica fumes was negatively correlated with it.