Abstract: Aiming at seamless turnout on bridge, the rail-turnout tie-bridge spring-damping vibration model was built by using finite element method. The train-turnout-bridge spatial vibration equation sets were formulated by using the principle of total potential energy with stationary value in elastic system dynamics and the “set-in-right-position” rule for formulating matrixes. Taking Tian-luo major bridge in Wenzhou-Fuzhou railway line for passenger as an example, it was assured that there was a crossover combined with two No.38 turnouts on the bridge. The train-turnout-bridge spatial vibration dynamic responses were analyzed when “China Star” high speed train with 1 locomotive and 4 passenger cars at the speed of 140km/h through turnout branch. The influences of train velocity, the lateral stiffness under rail, the lateral uniform stiffness under tie and the height of pier to the train-turnout-bridge system vibration were analyzed. The results show that bridge leads the displacement of rail and turnout tie increase very much, the dynamic responses of train increase a little, and it has little effect to the acceleration of turnout and wheel/rail force. The system responses increase with the increasing of train velocity, the decreasing of lateral stiffness under rail, the decreasing of lateral uniform stiffness under tie, and the increasing of pier height.