Considering the non linear characteristic of chloride binding, the diffusion characteristics of chloride diffusion in modeled recycled aggregate concrete(RAC) was numerically simulated. The effect of relevant parameters (i.e., the replacement ratio of recycled coarse aggregates, old interfacial transition zone(ITZ) diffusivity, immersion time and the thickness of old adhered mortar) on the diffusion properties of modeled RAC was investigated. The results of parameter study indicate that the distribution of chloride ion concentration is non uniform in the modeled RAC; the effect of non linear characteristics of chloride binding on chloride diffusion is significant, and the chloride ion concentration in RAC declines wavily along the diffusion depth. Furthermore, the influences of recycled coarse aggregate, immersion time and the thickness of old adhered mortar on the variation of chloride ion concentration become pronounced with the increasing depth, and this is more remarkable at the ITZ.