Abstract: Steel structure rust reduces the plastic of steel and accelerates crack propagation, which has great influence on the seismic performance of steel structures. With the help of accelerated corrosion test, the relationships between steel strength, ductility index and corrosion degree are established. In this paper, the relationships between the damage state of steel structure and the degree of corrosion of steel structure under earthquake action are studied, and the value of the displacement angle between the frame layer of corroded steel is proposed based on the limit failure state. The influence of corrosion resistance on the seismic performance of steel frames is discussed by using the static elastoplastic analysis method. Using the incremental dynamic analysis method, to establish the relationship between the structural damage index and the ground motion intensity index, the earthquake vulnerability curves of corroded steel frames of different ages are obtained. An earthquake vulnerability assessment method of corroded steel frames is established. The results show that different limit states of the same age have different probability of exceeding the limit state, and the gap between the limit state of collapse is relatively large, while the difference of serviceability limit state is small. The seismic performance of rust steel frames can be overestimated if the interlayer displacement angle limit is not corrected.