Abstract: Taking reinforced concrete columns which are seriously damaged as the research subjects,it is researched the seismic behaviors of the repaired columns.The concrete of columns in the plastic-hinge zone is replaced with grout material and the columns are strengthened with unidirectional CFRP.Then,the experiments are done under low-cyclic and repeated load for the strengthened columns.The cracks development and the deformations of the specimens are observed.The normal section bearing capacity of the columns is analyzed,and the hysteretic curves of loading and displacement are drawn out.Whose results are compared with the performance of the column without pretreatment in order to study the behaviors of capacity and deformability of the repaired and strengthened specimens.By contrasting the experimental values with the values calculated by The Code for Reinforcement Design of Concrete Structures(GB 503672006),the repaired and strengthened specimens are safety.Compared with the column without pretreatment under the same condition,the bearing capacity and the hysteretic area of the repaired and strengthened ones are increased,and the ductility and energy-absorbing capacity are significantly improved.