Dynamic analysis of PSC box bridge bearings for high-speed KTX train vehicles has been carried out to evaluate a running safety of train. Improved numerical models of bridge/vehicle and interaction between bridge and train are adopted, where bending and torsional modes are considered. Dynamic/static sliding distances of the bearings according to the KTX running speed are proved as a major parameter rather than the AASHTO and EN1337-2 focused on the distance by temperature variations.