Abstract: The vibration response of track and roadbed under dynamic action is one of the keys to solve the problem of safe operation of high-speed trains on track. To ensure the security of high-speed rail during an earthquake, based on ABAQUS and FORTRAN subprogram methods, a three-dimensional refined model was established that included ballast-less track, subgrade and foundation of high-speed railway, which were analyzed in detail including the influence of seismic-train moving load characteristics on track structure and instantaneous derailment standard. The critical speed and derailment mechanism of high-speed train under the action of a large earthquake were discussed. The derailment criteria considered included the ratio of the transverse force to the vertical force (derailment coefficient) and the transverse deformation of the track, so as to seek reasonable improvement and minimize the risk of major earthquake. Results show that when the seismic action and train moving load act together, the former has a significant effect on the vertical positive displacement of the rail, and its acceleration and frequency spectrum are more prominently affected the latter. Meanwhile, the train derailment probability significantly increases. The critical speed of the rail is 50 m/s(180 km/h). At this time, the rail lateral displacement is large, and the derailment coefficient curve changes sharply, which seriously exceeds the national safety standards. The train may lose stability or even derail.