In order to ensure safety of long and huge bridges in deep water under earthquake action, it is significance to consider water and bridge pier dynamic interaction. Analysis method of water-bridge pier dynamic interaction under earthquake excitation is established using radiation wave theory, and earthquake induced hydrodynamic pressure apply program is complied. Considering different earthquake wave input, earthquake induced hydrodynamic pressure influence on dynamic responses of bridge pier in deep water is further studied. The results indicate that: Dynamic response of bridge pier in deep water is augmented because of hydrodynamic pressure action. Earthquake induced hydrodynamic pressure influence on seismic responses of bridge piers in deep water will change with different input earthquake wave.