In order to understand the dynamic behaviors of deep reinforced concrete (RC) beams under impact loadings, falling-weight impact tests on two groups of simply-supported deep RC beams with different static behaviors were carried out and the effects of impact velocity and the second impact on the impact-resistant behavior of deep RC beams are investigated. By analyzing the crack initiation, propagation and the failure process of the specimens recorded using a high-speed video camera and comparing the crack patterns of specimens under different loadings, it is found that the crack initiation, propagation, the failure process and crack patterns are affected obviously by impact velocity and the major crack development under the second impact mainly follows the crack path induced by the first impact loading. The characteristics of time histories of impact force and mid-span displacement and impact force versus mid-span displacement curves are described in details and that the maximum impact force, the maximum mid-span deflection, the residual mid-span deflection change approximately linearly with impact velocity for specimens without serious shear failure is observed. Moreover, the specimens with better ductility have better impact-resistant behaviors. Finally, by analysis of the time histories of impact force, supported reaction force and inertia force, it is deduced that taking the maximum impact force or the maximum support force as the impact-resistant loading capacity is irrational.