A pedestrian bridge suspended to a vehicular bridge to form a combined bridge, can provide passages not only for vehicles but pedestrians. However, the vibration comfort of the suspended pedestrian bridge under vehicle excitation from the vehicular bridge still needs to be discovered. In this paper, fundamental frequency estimation formulas applied to the suspended pedestrian bridge are proposed and verified through finite element method. Results show that fundamental frequencies of the suspended pedestrian bridge depend largely on dynamic characteristics of the vehicular bridge. The vehicle induced vibration of a long-span suspended pedestrian bridge is analyzed through separated iteration methods. Results show that the vibration responses become larger with worse road condition or higher density traffic flow. The vibration responses have no evident relationship with vehicle speed. The vertical acceleration peak of the pedestrian bridge in mid-span under vehicle excitation exceeds half of that excited by pedestrian. Therefore, the vehicle induced vibration effect should be considered in the comfort evaluation of pedestrian bridges suspended to vehicular bridges, which will decrease the pedestrian comfort.