The butt welding test was carried out on the 6 mm thick 5454-H24 /6106-T6 aluminum alloy sections by fiber laser-CMT hybrid welding processes. After the optimization of the process parameters, the well-formed welding joints were obtained. On this basis, the 1, 2 and 3 repair welding were performed respectively. The microstructure and mechanical properties of the joints after multiple repairs were analyzed, and the thermal crack sensitivity of the joints was evaluated. The results show that the weld cross section of the obtained butt joint and the three repairs joints are both typical "Y" type. As the number of repair welding increases, the weld width increases, and the corresponding heat affected zone (HAZ) range is wider. The microstructure of the weld zone is enlarged and the tendency of the pores is increased. The tensile strength and yield strength of the hybrid welded joint are reduced, and the welded joint is broken at the weld. After repair welding, the microhardness of the heat affected zone on the 6106 side decreased, while no obvious decrease occurred in the heat affected zone on the 5454 side. After the repair welding, the thermal crack sensitivity increases. Three repair welds can be carried out under the condition that the process is well controlled and the welding defects are reduced.