The study is mainly aimed at the effect of steel corrosion on bond strength of reinforced concrete. The parameters involoved are w/c and corrosion prevention strategies, etc. The result indicated when clear distance between reinforced steel was over 4 times of concrete cover thickness or the lateral protective layer was over 2 times as concrete cover thickness, the crack pattern of concrete after corrosion would be radial fracture; if not so, it would be spalling fracture. The rate of weight loss and bond strength of corrosion was in inverse relation; hence, when weight loss rate was up to 1.7%,the structure safety would be damaged. Learning from the microstruction study, if there was a pore or rust in the bond interface, it was liable to be the source of micro crack. These microcracks and the calcium hydroxide crystal from bleeding in aggregate boundary would affect the bond stress.