In order to explore the corrosion characteristics of steel bars in cracked concrete under carbonation, the carbonation law of cracked concrete under carbonation was studied by controlling the crack parameters, and the characteristics of corrosion area rate, weight loss rate and electrochemical corrosion parameters of steel bar were clarified. The results show that the crack width of the hardened cement paste with cracks in the early stage of curing has a more significant effect on the corrosion of steel bar than the water-cement ratio, and the influence of the crack width on the corrosion of steel bar gradually increases in the later stage of curing, and the influence of the crack width on the corrosion of steel bar is dominant. There are two capacitive arcs in the Nyquist diagram of a cracked hardened cement paste under carbonization. As the age of carbonization increases, the capacitive arc resistance in the low-frequency region gradually shrinks, the transfer resistance of the electric double layer on the surface of the steel bar decreases, and the steel bar begins to remove the passivate film. Within a certain range of crack width, when the water- cement ratio is small, it can suppress the corrosion of the steel bar. The investigation into the impact of carbonization on the corrosion of cracked reinforced concrete is valuable for enhancing the non-destructive testing technique of reinforced concrete.