Abstract: According to the test of mechanical property of friction pendulum isolators and design parameters of a typical Chinese high-speed railway bridge, the finite element method is used to model a general simple support beam bridge in Chinese high-speed railway. Based on the characteristics of the response spectrum in different sites, a comparative method in the probability seismic demand model of a high-speed railway isolation bridge under different site conditions has been put forward. By means of the methods proposed, the effect law of site conditions on the probability seismic demand model of a high-speed railway isolation bridge has been studied.