The quasi-high-speed train and reinforced concrete multi-span box girder bridge are considered as an integral vibration system in analysis. In accordance with random vibration energy theory1, and by taking artificial hunting curves of the train frame as excitation source, vibrating responses with 99% probability of the train and bridge system are calculated when a quasi-high-speed train runs through the reinforced concrete multi-span box girder bridge respectively at a speed of 160 km/h and 200 km/h.