Abstract: The vehicle was modeled as a seven-degree-of-freedom system, and the cracks on the concrete beam were classified as open crack zone and breathing crack zone. This paper established the coupling equations of motion for vehicle and the multi-span cracked concrete beams with varied sections, and then, the corresponding computer program was developed and validated further. The effects of some parameters on the impact factor of the damaged concrete beams were studied, including crack types (open crack or breathing crack), crack location, crack components and vehicle number. The results show that the impact factors increase with the presence of crack zone, and the effect of open crack zone on the impact factors is more significant than that of breathing crack zone; the impact factors relate to crack components, crack position and the vehicle number on the beam.