Based on microcapsule technology, a new type of self-healing system for cementitious composites is established. The performance of the system was characterized by means of electrochemical impedance spectroscopy of steel bars immersed in a simulated concrete environment. The results demonstrate strong inhibition of chloride-induced corrosion when microcapsules are added to the solution. A novel equivalent circuit model, which takes into account the inductive effect arising from the generation of corrosion products on the steel bar surface, is proposed to explain the protection performance of the microcapsules against steel bar corrosion in a concrete environment.