High-pier railway bridges are widely used in mountainous areas with complicate, rugged and dangerous landform. Due to the large spatial flexibility of the high pier, the wheel-rail dynamic interaction may become more intense under the combined action of the train dynamic load and the non-stationary seis-mic wave, which may cause greater deformation and impact on the train-track-bridge (TTB) coupling system. In order to study the structural dynamic characteristics and traffic safety of such a complex and large-scale system under earth-quake conditions, this work proposed a train-track-high pier bridge (TTHPB) spatial coupled dynamic model and verifies its the accuracy and reliability by comparing with published literature. In this model, the multi-rigid-body train, the elastically point supported Euler rail, the Mindlin track slab considering shear deformation, and the finite element model of the high-pier bridge with variable cross-section continuous beam and tapered hollow pier are properly considered. In the simulation of the ground motion, traveling wave effects, soil conditions and coherent effects are comprehensively considered, and the corresponding acceleration time history sequence is generated for each support position of the high pier bridge by spectral method. The influences of the pier heights and train speeds on the train running safety are systematically investigated. This work provides theoretical reference for the design of high pier bridges and the speed of trains passing through the bridge in earthquake prone areas.