The　objectives　of　this　paper　are　to　perform　a　comparative　analysis　of　the　large-scale　system　of　a　high-pier　railway　bridge　subjected　to　stationary　and　non-stationary　spatially　varying　earthquake　excitations　using　the　pseudo-excitation　method　(PEM),　and　to　estimate　whether　or　not　the　non-stationary　stochastic　analysis　of　the　high-pier　railway　bridges　under　tri-directional　spatial　ground　motions　can　be　simplified　into　a　stationary　random　analysis　to　avoid　excessive　computation.　Based　on　the　finite　element　software　ANSYS,　the　stationary　and　non-stationary　stochastic　excitations　analyses　of　a　high-pier　bridge　were　transformed　into　harmonic　analyses　and　deterministic　transient　analyses　in　the　study,　respectively,　by　using　PEM.　The　wave-passage　effect　and　the　incoherence　effect　were　modelled　as　the　key　factors,　a　total　of　twelve　cases　were　considered　to　investigate　the　wave-passage　effect　and　incoherence　effect　on　the　seismic　response　of　a　high-pier　railway　bridge　under　stationary　and　non-stationary　earthquake　excitations.　Results　show　that　structural　responses　under　stationary　excitation　are　larger　than　those　under　non-stationary　by　considering　either　the　wave-passage　effect　or　the　incoherence　effect.　Through　comparing　structural　responses　under　stationary　excitation　with　those　under　non-stationary　one,　all　the　growth　rates　are　less　than　25　%,　which　is　acceptable　in　engineering,　meaning　that　a　non-stationary　stochastic　analysis　of　high-pier　railway　bridges　under　tri-directional　spatial　ground　motions　can　be　simplified　into　a　stationary　analysis　to　avoid　excessive　computation.