Abstract: The dynamic model of vehicle-bridge system is established in this paper, in which the vehicle subsystem is modeled by rigid body dynamics method; the bridge subsystem is modeled by finite element method; the movement of wheel set is assumed as sum of track movement, track irregularity and hunting movement. The solving method and the characteristics of the response for vehicle-bridge interaction system are studied. A 24m simple-supported girder of the Gouhe Bridge in the Qinghuangdao-Shenyang Special Passenger Railway is chosen as a case. The displacement and acceleration responses of the bridge are filtered in order to analyze the frequency components of them. The sensitivities of the track irregularity, hunting amplitude and hunting wavelength for the vibration in the mid span of the bridge are discussed.