Abstract: A simplified single-degree-of-freedom (SDOF) hysteretic model for collapse analysis of building structures is proposed in this work. The simplified hysteretic model is capable of simulating strength deterioration under monotonic loading, pinching, strength and stiffness deterioration under cyclic loading as well as P-Δ effect, so that it can be applied to collapse analysis. To validate the applicability and effectiveness of the proposed SDOF hysteretic model, an eight-storey RC frame structure is simplified as an equivalent SDOF system according to its fundamental mode of free vibration and the collapse fragility analysis based on incremental dynamic analysis is implemented to the prototype structure and the simplified SDOF system, respectively. The results show that the collapse fragility curves of the prototype structure and the simplified SDOF system agree quite well with each other.