In this paper, a quarter vehicle model and a uniform cross section simply supported beam model are used to establish a vehicle bridge coupling system. The global maximum values and its location on the bridge of dynamic deflection, dynamic bending moment and dynamic shear force are analyzed when the vehicle travelling through the bridge at a constant speed. The effects of vehicle speed, distance between front and rear vehicles, and bridge modal truncation order on the global maximum value are further analyzed and calculated. The results show that the vehicle speed has a greater impact on the global maximum value of dynamic deflection, dynamic bending moment, and dynamic shear force of the bridge. Both the global maximum dynamic deflection and the global maximum dynamic bending moment appear in the mid-span range, the locations are different with different vehicle speeds. The global maximum dynamic shear force appears at the beam end of the vehicle exiting the bridge. when two vehicles are on the bridge at the same time, the greater the distance between the front and rear vehicles, the smaller the global maximum value of dynamic deflection, dynamic bending moment, and dynamic shear force of the bridge. When a certain distance is reached, the global maximum values are no longer reduced and are the same as the case of a single vehicle. In order to improve the calculation accuracy of the dynamic deflection, dynamic bending moment, and dynamic shear force of the bridge, the bridge modal truncation order should be greater than 3 orders, 6 orders and 7 orders, respectively.