Abstract: Based on numerical simulation, the paper took a 5-story, an 8-story and a 12-story reinforced concrete frame structures as research objects and did random incremental dynamic analysis (IDA) under 20 ground motions. Adopting performance-based seismic design theory, it proposes a method to confine the yield and collapse capacity value for structures. Based on this method, we get the seismic fragility curves of yield and collapse damage levels of each model. The results show that the yield and collapse capacity value can be obtained using corresponded fragility curves which have 95% confidence level with 5% probability of yield and collapse. By comparing the yield and collapse fragility curves, the fragility parameters are influenced by the variation of structure storey.