To explore the effect of canyon topography on the seismic response of railway irregular bridge-track system that crosses a V-shaped canyon,seismic ground motions of the horizontal site and V-shaped canyon site were simulated through theoretical analysis with 12 earthquake records selected from the Pacific Earthquake Engineering Research Center(PEER)Strong Ground Motion Database matching the site condition of the bridge.Nonlinear seismic response analyses of an existing 11-span irregular simply supported railway bridge-track system were performed under the simulated spatially varying ground motions.The effects of the V-shaped canyon topography on the peak ground acceleration at bridge foundations and seismic responses of the bridge-track system were analyzed.Comparisons between the results of horizontal and V-shaped canyon sites show that the top relative displacement between adjacent piers at the junction of the incident side and the back side of the V-shaped site is almost two times that of the horizontal site,which also determines the seismic response of the fastener.The maximum displacement of the fastener occurs in the V-shaped canyon site and is 1.4 times larger than that in the horizontal site.Neglecting the effect of V-shaped canyon leads to the inappropriate assessment of the maximum seismic response of the irregular high-speed railway bridge-track system.Moreover,engineers should focus on the girder end to the left or right of the two fasteners within the distance of track seismic damage.