The essence of the axle coupling vibration in case of random bridge deck is random vibration, therefore, it is quite necessary to research the effect of vehicle impact on basis of statistic analysis. With some large concrete-filled steel tube arch bridge as the object, by applying a self-made analysis program on axle coupling vibration that was demonstrated by a dynamic test, a dynamic response analysis on axle was implemented for many groups of random roughness swatches. On basis of the analysis result, a statistic analysis was conducted for the dynamic impact effect of bridge under the conditions of different deck status and vehicle speeds, in the determination of vehicle speed and roughness, the impact factor obeys the normal distribution. The analysis result shows that, the level of deck status may apparently affect the mean value and the MSD(mean square deviation), the differences of vehicle impact factors in case of different assurance rates are large. It will effectively improve the reasonableness and scientificalness of the value of a vehicle impact factor to determine the impact factor according to the level of bridge importance and a statistic analysis method.
