Dynamic performance of bridge is influenced by river scouring. In order to study the effect of scouring on vehicle-bridge interacted vibration, erosion depth of pile group foundation is calculated. With the consideration of the variation of equivalent stiffness of foundation induced by scouring, a vehicle-bridge coupled dynamic model based on inter-system iteration is established. In case study, dynamic response of vehicle-bridge system and running safety of trains before and after scouring is contrasted. The results shows that, for a railway bridge located in the river and tidewater, the vehicle-bridge model considering river scouring is proposed to analysis the vehicle-bridge interacted vibration. After scouring, all bottom surfaces of pile caps come above the river bed, and equivalent stiffness of foundation decreases significantly. The lateral responses of both simply supported bridges and vehicles increase obviously. It might even influence the running safety of trains.