The performance of recycled aggregate (RA) was improved by pre-soaking the RA in nano-SiO2 solution to enhance its weak surface. A mesoscopic model of multi-phase for recycled aggregate concrete (RAC) was established to simulate the chloride ion transportation in concrete. Experiments of RAC immersing in chloride ion solution were carried out to verify the simulation results, and service life of RAC exposed in chloride ion environment was predicted. The results indicate that the mesoscopic numerical simulation results are in good agreement with the experimental results. At the same depth, the closer to the aggregate surface, the greater the chloride ion concentration, and the concentration of chloride ion on the surface of un-strengthened RA is higher than that on the surface of strengthened RA. Increasing the thickness of protective layer effectively improves the durability life of the nano-strengthening RAC in chloride environment. The durability life of RAC increases a little with the decrease of chloride ion diffusion coefficient of nano-coating layer.