Abstract: Based on the performance of the seismic design concept for the concrete dam, the incremental dynamic analysis method (IDA) is adopted to evaluate the seismic performance of the gravity dam according to the results of the sub-analysis. Taking the Koyna gravity dam as a case study, the traditional model with massless foundation and added mass method and the seismic dam-foundation-reservoir interaction model with the viscous spring boundary and fluid-solid coupling method are respectively developed in this study. 16 earthquake records are taken as the ground inputs; the ground peak acceleration is selected as the earthquake strength index and the relative displacement of the crest as the structural performance index. Then, the IDA curves are plotted and the results of the two models are compared. The research results show that the new model has a high overall safety redundancy for the PGA with different guarantee rates, which is about 10% ~ 20% higher as compared to the traditional model. And the calculation results of the seismic analysis model established by the traditional method are conservative; the ultimate seismic capacity of the Koyna dam is about 0.45g, and its function guarantee level is about 0.34g. The traditional method is conservative and the incremental dynamic analysis method will also provide a new idea for the seismic design of dams in the future.