In order to study the influence of nodal rigid zone on the dynamic responses of a steel-concrete composite trussed girder bridge under high-speed train, one railway bridge is taken as a numerical example and the self-developed software TRBF-DYNA is utilized to calculate the dynamic responses of train-track-bridge coupled system. The whole three-dimensional model of the track-bridge subsystem is established by using finite element method, where each vehicle of the train is modeled as 31 degrees of freedom model by applying the rigid-body dynamics theory, and the spatial rolling contact model is used to simulate the interaction between wheel and rail. Firstly, the influence of nodal rigid zone on the bridge vibration characteristics is studied. Then, the effects of the nodal rigid zone and running lane on the vehicle running safety indexes and dynamic responses of local steel truss webs and global bridge are investigated. The analysis results show that the nodal rigid zone improves the stiffness of the bridge. Meanwhile, the maximum vertical displacement and vertical acceleration of the bridge are reduced by 30.00%~35.15%. Moreover, the internal force of steel truss webs increases significantly, particularly the bending moment increases up to 90.41%~224.02%, and the nodal rigid zone has little influence on the safety indexes of vehicle. Compared with single-lane driving, the dynamic responses of the bridge with double-lane driving are markedly increased, and the peak value of the lateral and vertical accelerations are increased by 114.29% and 100%, respectively. Stress of the steel truss webs increases, but it is not linearly increased according to the number of running lane. It is suggested that the influence of the nodal rigid zone should be considered in the evaluation of the dynamic responses of steel-concrete composite trussed girder bridges.