An　efficient　numerical　model　is　presented　to　calculate　the　earthquake-induced　hydrodynamic　forces　and　wave　forces　on　an　inclined　circular　cylinder　with　arbitrary　angle　to　the　seabed.　A　finite　water　domain　close　to　the　cylinder　is　discretized　into　conventional　three-dimensional　finite　elements.　A　cylindrical　absorbing　boundary　is　used　to　simulate　the　remaining　infinite　water　domain.　According　to　the　boundary　conditions,　the　exact　solution　of　the　absorbing　boundary　condition　is　derived　by　using　separation　variable　method　in　the　cylindrical　coordinate　system.　A　coupled　equation　is　obtained　by　adding　the　impedance　matrix　of　infinite　domain　to　that　of　finite　domain.　The　proposed　models　are　verified　using　the　analytical　solutions　of　the　earthquake-induced　hydrodynamic　forces　and　wave　forces　on　a　vertical　circular　cylinder.　The　wave　forces　and　earthquake-induced　hydrodynamic　forces　on　inclined　circular　cylinders　are　furtherly　investigated.　Finally,　the　added　mass　for　an　inclined　circular　cylinder　vibrating　in　water　is　studied　and　a　simplified　formula　of　the　added　mass　is　also　presented　in　the　present　study.