Abstract: Recently, accidents of collisions between over-high trucks and bridge superstructures happen frequently, which seriously threaten the safety of bridges and city traffic system. In order to reduce the loss due to the over-high-truck-to-bridge collision, the collision resistance of bridge superstructures need to be strengthened, on which the research is still very lack currently in China. Based on the high-precision nonlinear finite element simulation and accident investigation, this paper discusses the damage mechanism and collision loads of impact between over-high trucks and bridge superstructures. Study results show that the damage modes of bridge superstructures impacted by over-high trucks include global deformation damage, local damage and girder-falling. The impact loads that controls the damage modes include the collision impulse and the local punching force, which differ a lot for different types of trucks