A　study　of　the　dynamic　response　of　a　circular　bridge　pier　forced　simultaneously　by　earthquake　and　wave-current　actions　is　presented.　On　the　basis　of　diffraction　wave　theory,　the　analytic　solution　for　the　diffraction　of　incident　waves　with　uniform　current　on　a　circular　pier　is　given.　On　the　basis　of　the　radiation　wave　theory,　the　analytic　solution　for　the　hydrodynamic　pressures　on　a　circular　pier　induced　by　combined　earthquake　and　wave-current　action　is　obtained.　Further,　the　solution　for　the　dynamic　responses　of　the　pier　under　combined　earthquake　and　wave-current　action　is　obtained　by　treating　the　pier　as　a　cantilever　beam　governed　by　beam　theory.　Last,　the　effects　of　hydrodynamic　force,　wave　force,　wave-current　interaction,　and　surface　wave　condition　on　the　dynamic　responses　of　the　pier　are　investigated.　The　results　may　be　used　for　engineering　practice　and　further　research.