In order to reasonably describe the seismic damage forms of corroded steel frame and the effects of different levels of corrosion on the seismic performance of steel frames, on the basis of the seismic damage model of steel structure which is proposed by Ou Jinping, et al, the seismic damage model of corroded steel frame is built. To determine the seismic damage model parameters of corroded steel structure, the calculation methods of the bilinear restoring force model feature points of corroded beams and columns member are given, and other model parameter values are obtained by elastic-plastic time history analysis. Using the weighted partial coefficient method to study the multi-scale effect of migration and transformation from member damage to structure damage, the overall seismic damage model of corroded steel frame is established. Combined with the characteristics of damage model in this paper, the corresponding structural damage index ranges with different damage levels are defined. Finally, elastic-plastic time history analysis has been performed for 5 specimens of flat steel frame structures with different corrosion rates, the results show that the damage model in this paper can reflect the degradation of steel frame structure with the corrosion degree in the certain degree.