The influence of atmospheric pre rusting on the chloride induced corrosion behaviors of low alloy(LA) rebar and conventional low carbon(LC) rebar in simulated concrete pore solution(SCPS) was investigated using electrochemical impedance spectroscopy(EIS) and surface analysis techniques(BSE images and EDS analysis). The results indicate that, the formation of passive film for both rebars is slightly influenced by pre rusting and the reduced corrosion resistance of LC rebar can be observed after chlorides attack. However, the long term chloride induced corrosion behavior of LA rebar is not affected by pre rusting. The main reason is that compact Cr enriched corrosion products are gradually formed for LA rebar, thus fill the crevice between rebar substrate and prevent from the further attack by chlorides.