In order to obtain the dynamic response characteristics of bridges under the action of current and wave, taking the continuous beam of a 4-column pile column frame pier as the object, a bridge (pier)-water interaction numerical analysis model is established by using ANSYS. The flow around piers under the action of water flow is analyzed. The dynamic responses of the single pier and this pier in bridge span structure under different flow velocity, different wave height and the combined action of wave and current are studied. The results of the flow analysis show that the velocity field and pressure field of each column are asymmetric. When the flow acts alone, the dynamic response increases with the increase of flow velocity and water depth. Compared with the single pier, the dynamic response of water flow to the pier in the bridge structure is small, and the dynamic response of deep-water bridge gradually increases with the increase of velocity and water depth. When the wave acts alone, the dynamic response of the pier in the single deep-water pier and the pier in bridge span structure produces the maximum value when the wave crest acts and the minimum value when the wave trough acts. With the increase of wave height, the dynamic response of the single pier and this pier in bridge span structure increases at the peak and trough and basically increased linearly. With the increasing water depth, the dynamic effect of waves on the single pier and this pier in bridge span structure becomes more and more significant. Under the combined action of wave and current, the dynamic responses of the single pier and this pier in bridge span structure increase with the increase of wave height and water depth. The maximum value of dynamic response at the peak increases with the increase of flow velocity, and the maximum value of dynamic response at the trough decreases with the increase of flow velocity. The maximum current influence coefficient is 12.96%, indicating that waves play a leading role in the dynamic response. When the direction of wave and current is the same, the dynamic response of the combined action of wave and current is not the superposition of the two alone.