The accuracy of seismic response results significantly depends on the exactness of the Finite-Element Model（FEM）.This paper took a representative three span continuous bridge as an example. The methods for model different components and boundaries of the bridge were summarized and investigated systematically, and three approaches were adopted to establish three nominally identical bridge models. Then, the same seismic record was selected to conduct the time-history analysis, and the response results of the three models were compared. The numerical results have revealed that it is improper to evaluate the bridge seismic behavior with the traditional simplified model because of the error and impreciseness, and the results can hardly reflect the nonlinear response of the bearing, blocking and expansion joint,et al. However, this accurate model can reveal the accuracy and exact seismic response. In addition, it is even more adoptable for the performance-based bridge seismic design.