Abstract: Based on the salt spray test of reinforced concrete beams, the ductility of reinforced beams of the corrosion condition of chloride ions was analyzed. With the parameter amendment method and combining the experimental conditions, the computation model of the section curvature ductility factor of reinforced concrete beams under corrosion condition was worked out on the basis of existing section curvature ductility factor formula. The comparison between the calculation results from the model and the experiment results showed that this new model might reflect the rules of ductility changes of corroded parts and thus could provide theoretical bases for evaluating the firmness of been corroded reinforced concrete beams.