Abstract: In view of the problem of repairing Canopy sealing weld of drive structure of the pressure vessel in the third generation nuclear power reactor, the failed weld was cut and rewelded for repair in the paper. The repair process of Canopy weld after cutting and rewelding was studied, and the process from cutting to rewelding was discussed, as well as non-destructive testing and microstructure analysis of the rewelded weld. At the same time, the rewelded joint was compared with the welded joint that only underwent one welding with the same process, and the macrostructure and microstructure of the joint were compared and analyzed, so as to evaluate the quality of the rewelded joint. The test results showed that through controlling cutting quality of the weld and grinding the groove after cutting, the weld could be rewelded under the original process, and the rewelded weld passed the nondestructive testing. There were no harmful precipitates in the microstructure of the joint, and the weld quality was equivalent to that underwent only one welding. It was proved that the scheme of rewelding the failed welds after cutting could be used for the repair of Canopy welds.