The procedure of beam subjected to transverse impact by bar is simulated using numerical method. The method considers the propagation of the expansion wave and shear wave in beam. The effect of beam height on elastic impact loads with different bar lengths and beam heights are investigated. With condition that the length of beam is longer than or equal to that of bar, the numerical solution shows that: when the bar length is constant, if the length of bar is shorter than the height of beam, the longer the bar, the bigger the peak value of impact force; the impact load curve consists of ascending and descending part basically; When the bar length is longer than or equal to beam height, the peak value of impact force is not related to the bar length and equal to that of bar with the same length as the beam height; the impact load curve is trapezium. The contact time is proportional to bar length and equal to the duration time of stress wave propagation in the bar for once return. If the bar length is constant, when bar length is shorter than beam height, the impact load is not related to beam height; when bar length longer than or equal to beam height, the peak value of impact force increases along with the beam height and approach to that of bar with the same length as the beam height.