In order to ensure that the high-speed railway system can continue to operate during the earthquake relief period and the rescue materials and medical forces can be transported, it is necessary to reasonably predict seismic-induced geometric irregularity. In this work, a finite element model of a simply-supported high-speed railway beam bridge with the China Railway Track System (CRTS) Ⅱ was established using ANSYS. A total of 60 seismic waves were arbitrarily selected from the PEER strong ground motion database. Nonlinear time-history analysis was carried out based on the finite element model, and the distribution mode of residual track irregularity after earthquakes was summarized. A method of constructing power spectral density curve of seismic-induced geometric irregularity was proposed, and the sample was generated. The simulation method of track irregularity after earthquake was discussed. The results show that: under the action of transverse earthquakes, tracks suffered obvious alignment, cross-level and vertical irregularity, and the amplitude for gauge irregularity was small the power spectral density of residual track random irregularity at each frequency obeys lognormal distribution; the spectrum of seismic-induced track geometric irregularity can be simply expressed by the mean and variance of the spectrum set of track residual irregularity; the effect of initial irregularity on seismic-induced irregularity can be neglected, and the track geometric irregularity after earthquake can be approximately regarded as the sum of initial irregularity and seismic-induced irregularity.