In order to study the sensitive influence parameters of the impact factors for rigid-continuous combined bridge, finite element model was set up based on the bridge-vehicle coupled vibration, the vehicle of which adopted three axles half-car model. The influence parameters included the ratio of bridge and vehicle frequency, the roughness of deck, the mass of vehicle, the damping ratio of vehicle, the velocity of vehicle, the driving mode of vehicle, the rigidity of bridge, the arrangement of bridge and the soil-structure–interaction mode, then orthogonal test table was employed to study the structural impact factors of deformation and bending moment in the critical sections under those parameters respectively, thus the sensitive parameters could be found. The results show that the impact factor of the combined bridge calculated by impact formula of General Code for Design of Highway Bridges and Culverts is relatively lower, and the ratio of bridge and vehicle frequency, the roughness of deck, the velocity of vehicle are the sensitive parameters affecting the impact factors. Therefore the impact factor should be interpreted as the function of muti-parameters rather than only one parameter.