Abstract: Addressing the problems of the dissatisfied morphology and quality of the defective weld of the small-sized SAWH pipe as repaired, and the low one-time pass rate of the repair-welding, accordingly a set of simple-operation repairwelding system is designed. Described here in the paper are the design ideas, the main structure, and the actual application effectiveness of the said system, as well as the quality of the weld as repaired.The melting electrode active gas-shielded arc welding(MAG welding) process is adopted for the said repair-welding system. As a result, there are no problems like internal weld overlap and welding spatter occurring with repair-welding process.