The　study　of　dynamic　responses　and　operational　safety　of　high-speed　trains　under　seismic　excitation　has　increasingly　relied　on　numerical　simulation　as　the　most　effective　and　convenient　research　approach.　The　majority　of　studies　only　focus　on　single-car　formation,　and　fewer　utilize　train　models　with　actual　standard　formation,　inevitably　resulting　in　differences　in　dynamic　characteristics　of　train　models　and　simulation　results.　Furthermore,　trains　also　have　different　standard　formations　in　different　countries　and　operating　scenarios.　Therefore,　the　influences　of　train　formation　on　the　dynamic　responses　and　operational　safety　of　trains　under　seismic　action　are　investigated.　Hence,　a　detailed　train/vehicle-track　coupled　dynamics　model　was　established　to　simulate　trains　under　non-uniform　seismic　ground　motion.　Moreover,　due　to　wheel-rail　contact　simulation　being　the　key　factor　constraining　simulation　efficiency,　based　on　the　influence　pattern　of　train　formation,　whether　fewer　train　formations　can　achieve　the　same　simulation　accuracy　as　the　8-car　standard　formation　is　also　explored　in　this　paper　considering　seismic　wave　propagation　effect.　Results　indicate　that　variation　in　train　formation　can　influence　the　dynamic　responses　of　a　coupled　system　significantly　from　both　the　perspective　of　wheel-rail　interaction　and　vehicle　kinematic　responses.　Moreover,　the　5-car　formation　model　can　better　meet　the　accuracy　requirement　and　significantly　improve　computational　efficiency　compared　to　8-car　formation　model.