The finite-element model was used to simulate the double I-steel and concrete composite beam bridge with a span of 4×35 meters in the approach bridge outside the dike of Shouchun Huaihe River Bridge.The results indicate that the impact factor of the steel beam increases with speed and then decreases, reaching a maximum at 60 km/h. In contrast, the impact factor of the bridge deck continues to rise with speed, exceeding the design value of the standard local impact factor by 91.67% at 120 km/h. Both the steel main beam and the bridge deck’s impact factors decrease with the increase in vehicle weight. Specific trends in the variation of impact coefficients with vehicle speed and weight are identified, the limitations of existing bridge design codes in accurately describing the actual dynamic response to vehicle loading is revealed, the importance of considering local dynamic effects in bridge design and evaluation is emphasized.