Taking 4-span continuous beam bridge of high speed railway as the research object, the nonlinear dynamic model of isolation bridge with friction pendulum bearing (FPB) was established, and the energy response curves of isolation bridge under the earthquake wave of EI Centro were obtained. The friction coefficient and sliding radius of FPB were optimized based on the amplitude of response energy. The results showed that FPB had good energy dissipation capacity, which can effectively improve the seismic performance of bridge; when the seismic intensities were 7 and 8, the optimal friction coefficients were 0.03-0.04 and 0.05-0.06, and the optimal sliding radius were 2m and 2.5m. The friction coefficient needed to be increased properly with the increase of seismic intensity, and the isolation effect was basically unchanged when a certain value of sliding radius was reached.