Based　on　the　quasi-static　test　data　of　22　RC　cylindrical　piers,　the　calculation　accuracy　of　the　equivalent　plastic　hinge　lengths　in　piers　of　the　sharp-radius　curved　bridge　under　compression-bending-shear-torsion　coupling　is　examined,　and　with　the　torsion-bending　ratio　as　the　primary　influential　factor,　a　linear　regression　fitting　formula　is　proposed.　The　proposed　fitting　formula　and　the　calculation　formulas　given　in　different　specifications　are　evaluated,　against　the　test　results,　and　afterwards,　the　fitting　formula　is　modified.　The　results　demonstrate　that　the　torsional　effect　will　affect　the　equivalent　plastic　hinge　lengths　of　the　pier.　Given　that　the　proposed　fitting　formula　takes　into　account　the　impact　of　torsional　effect,　the　calculation　results　of　the　equivalent　plastic　hinge　lengths　under　the　coupling　effect　are　of　high　accuracy　and　guarantee　rate.　The　formulas　given　in　the　specifications　do　not　count　the　torsional　effect,　the　calculation　results　of　the　equivalent　plastic　hinge　lengths　are　highly　discrete,　which　will　lead　to　insufficient　design　safety　margin.　The　proposed　formula　is　proved　more　effective　in　calculating　the　equivalent　plastic　hinge　lengths　in　piers　under　compression-bending-shear-torsion　effect.　©　2022,　Journal　Press,　China　Railway　Bridge　Science　Research　Institute,　Ltd.　All　right　reserved.