To study the longitudinal seismic response and damage state of the high-speed railway track-isolation bridge system, a 7-span 32 m simply supported beam bridge with CRTSⅢ type ballastless track structure laid on the bridge deck was taken as the research object. A finite element model of the track-bridge system was established, and the seismic response distribution law of each key component under different seismic waves, seismic intensity and bearing types was obtained through nonlinear time-history analysis. The results show that the longitudinal displacement of the beam body presents a stepwise distribution under longitudinal seismic excitation, with the maximum value occurring at the center of the bridge span. The maximum displacement of the fastener occurs at the expansion joint of the abutment, and extreme values appear at the expansion joint at each beam end. The displacement of the fastener is significantly affected by the spectral characteristics of different seismic waves. The maximum stress of the rail occurs at the expansion joints on both sides of the side span, and the normal stress of the composite slab section is caused by the combined action of axial force and bending moment components. After the bearing and track system enter the nonlinear state, compared with the increase in seismic intensity, the increase in longitudinal deformation of the vulnerable components shows a significant amplification effect and distribution imbalance. Considering the track system, compared with the friction pendulum bearing, the same ball direction double spherical surface bearing can significantly reduce the displacement response of the fastener, beam body and bearing. The track system has a significant inhibitory effect on the displacement of the bearing.