In　order　to　solve　the　construction　and　anti-corrosion　problems　of　pier　of　sea-crossing　bridge,　a　new　structure　of　composite　pier　of　ultra-high　performance　concrete　(UHPC)　and　reinforced　concrete　(RC)　(short　for　U-RC　composite　pier)　was　designed,　and　UHPC　cylinder　was　taken　as　permanent　cylinder　to　cast　core　reinforced　concrete.　The　Pingtan　Strait　Bridge　was　taken　as　project　background,　the　structure　design　and　calculation　of　U-RC　composite　pier　were　carried　out,　and　the　workload　and　cost　of　U-RC　composite　pier　were　compared　with　the　ones　of　original　design　scheme.　The　ultimate　bearing　capacity　tests　of　three　core　reinforced　concrete　columns,　three　UHPC　cylinders　and　three　U-RC　composite　piers　were　carried　out,　the　longitudinal　and　transverse　strains　of　concrete　for　the　specimens　were　measured,　the　failure　modes　and　the　developments　of　cracks　were　observed,　the　test　values　of　ultimate　bearing　capacities　were　obtained,　and　the　mechanical　properties　of　U-RC　composite　pier　were　analyzed.　Research　result　indicates　that　the　bearing　capacity　of　U-RC　composite　pier　is　greater　than　the　design　value　of　internal　force,　which　meets　the　current　specification　requirement.　The　design　scheme　that　adopts　UHPC　cylinder　to　replace　steel　template,　can　save　about　2410　t　of　steel,　and　the　total　cost　saves　nearly　30%.　The　average　bearing　capacities　of　three　UHPC　cylinders　and　three　RC　columns　are　1342　kN　and　1370　kN,　respectively,　and　their　sum　is　less　than　the　average　bearing　capacity　of　three　U-RC　composite　piers(3033　kN),　which　indicates　that　the　UHPC　cylinder　has　certain　confinement　effect　for　core　concrete,　and　it　is　feasible　and　conservative　to　calculate　the　ultimate　bearing　capacity　of　U-RC　pier　under　axial　compression　with　simple　superposition　method.　In　the　axial　compression　experiment,　the　failure　mode　of　U-RC　composite　pier　is　that　the　lateral　deformation　of　core　concrete　leads　to　the　vertical　fracture　of　UHPC　cylinder　and　the　separation　of　UHPC　and　core　concrete　at　the　interface.　At　the　ultimate　load,　the　coating　UHPC　layers　have　vertical　cracks　that　grow　with　the　increase　of　the　load,　and　the　flaking　and　spalling　phenomena　of　concrete　appear.　But　when　the　U-RC　composite　pier　is　damaged,　the　longitudinal　strain　of　coating　UHPC　does　not　reach　the　ultimate　compressive　strain.　2　tabs,　14　figs,　25　refs.　©　2017,　Editorial　Department　of　Journal　of　Traffic　and　Transportation　Engineering.　All　right　reserved.