The bobbin tool friction stir welding 6005-T6 aluminum alloy profile joint was repaired once under the same process parameters,and the fracture surfaces of fatigue specimens were analyzed by SEM. The result of SEM scanning showed that,the fatigue strength of welded joints after repairing is lower than that of welded joints without repairing. With the increase of stress,the difference of fatigue strength between the two joints decreases from low stress zone to high stress zone.The fatigue limit of unrepaired welded joint is 101.7 MPa,and the fatigue limit of repaired joint is 75 MPa in lifting fatigue test. The Fracture analysis shows that,there are no obvious defects in the fracture surface of the specimen repaired once.The fatigue fracture position is mainly concentrated in the parent mental zone,the secondary crack propagation is less,the surface of the fracture initiation zone is smooth,and the fatigue beach are clear and gross. A large number of shallow dimples can be observed in the terminal area,which is a ductile toughness fracture.