Abstract: The tests of RC beams under lateral low velocity impact were simulated by the nonlinear finite element software LS_DYNA, including the effects of material nonlinearity and strain rate dependent, and the dynamic response and failure mechanism of RC beams were analyzed for the dynamic damage extension and impact energy transition. The results showed that the dynamic response of RC beams can be comprised of three stages: the local response stage, the overall response stage and the resilient stage; the damage of RC beam mainly occurred in the local response stage, the deflection of RC beam mainly occurred in the overall response stage; the impact force was completely balanced with the inertia force of RC beams within the local response stage, and the deflection model and axial distribution of the bending moment on cross sections were consistent with the rigid-plastic model within the overall response stage; the energy dissipation of tensile rebar by deformation was the foremost energy dissipation mechanism of RC beams under impact.