Initial　damage　often　exists　in　the　concrete　piers　of　bridges　in　service.　In　this　paper　numerical　analysis　was　used　to　study　the　seismic　strengthening　behavior　of　concrete　bridge　piers　with　different　bending　damage　degrees,　including　seismic　forces,　pier　top　displacements,　steel　bar　strain　and　energy　dissipation,　in　order　to　obtain　the　strengthening　demand　to　repair　the　damage　piers.　The　results　showing　that:　initial　bending　damage　reduced　the　seismic　force,　increased　the　pier　top　displacements　and　the　steel　bar　strain.　After　strengthening　the　pier　top　displacements　and　steel　bar　strain　at　the　pier　bottom　decreased,　energy　dissipation　increased,　and　the　anti-seismic　properties　of　damage　piers　effectively　recovered,　but　the　increase　of　the　seismic　force　might　make　new　plastic-hinges　out　the　strengthened　area.　At　last　according　to　the　mechanics　properties　the　strengthening　demand　under　different　bending　damage　degrees　was　given.　©　(2012)　Trans　Tech　Publications,　Switzerland.