Abstract: Currently，the seismic performance estimation is mainly based on the maximum structural displacement response caused by earthquake, while the seismic damage mechanism can not be revealed since the influence of hysteretic energy is ignored. In this paper, considering the characteristic parameters of seismic wave, an analytic method for calculating the SDOFS hysteretic energy is deduced based on non-linear vibration theory. Furthermore, the approximate relationship is established to convert the deformation and the hysteretic energy of MDOFS structure into that of equivalent SDOFS, and the Park-Ang model is applied to evaluate the overall seismic performance of structures. This method can reflect the mechanism of seismic damage, and is relatively high accurate, hence it can be widely used in engineering.