Precast　Segment　Bridge　Columns　(PSBCs),　which　attract　more　attention　owing　to　the　merits　of　faster　construction　rate　and　higher　construction　quality　compared　with　monolithic　columns,　are　prone　to　serious　damage　under　a　severe　earthquake.　Seismic　performance　improvement　and　rehabilitation　of　earthquake-damaged　PSBCs　are　significant　to　promote　applications　in　seismic-prone　areas.　Ultra-high　performance　concrete　(UHPC)　jackets,　which　are　promising　in　the　field　of　rapid　retrofit　of　civil　structures,　were　used　to　retrofit　damaged　PSBCs　in　this　study.　To　investigate　the　seismic　design　method　and　performance　of　repaired　PSBCs　using　UHPC　jackets,　a　1/10scale　earthquake-induced　damaged　PSBC　was　retrofitted　based　on　a　proposed　reinforcement　design　method,　and　tested　under　vertical　loading　and　incremental　lateral　cyclic　loading.　The　failure　mode,　hysteresis　curve,　residual　displacement,　and　energy　dissipation　capacity　of　the　repaired　column　were　compared　with　those　of　the　original　column.　In　addition,　based　on　a　verified　3D　finite　element　model　by　the　test,　a　parameter　analysis　was　conducted　to　explore　the　effect　of　the　height　and　wall　thickness　of　the　UHPC　jacket　on　the　seismic　behavior　of　the　repaired　PSBCs.　The　results　indicated　that　the　earthquake-damaged　PSBC　repaired　with　the　UHPC　jacket　had　an　equivalent　initial　stiffness,　18.9%　higher　energy　dissipating　ability　at　4.0%　drift　ratio　and　16.2%　larger　strength　compared　with　the　undamaged　column.　The　numerical　simulation　showed　that　the　height　and　thickness　of　the　UHPC　jacket　had　an　influence　on　the　failure　location　and　strength　of　the　repaired　PSBCs.　Besides,　the　design　method　for　the　damaged　precast　column　reinforced　with　the　UHPC　was　confirmed　by　the　test　and　finite　element　model,　and　it　could　be　applied　to　the　retrofit　design　of　the　damaged　precast　segment　column.