Abstract: Copper brazing and MAG welding were used for the seal welding of the lap joint of 0.8 mm + 2 mm stainless steel sheets. The appearance, metallographic structure, mechanical properties and corrosion resistance of the welding joints were compared and analyzed. The results show that the appearance, macro-metallography and microstructure of the two welding joints are excellent, and no surface and internal defects such as cracks, lack of fusion, lack of penetration, porosity, etc, are found in the welding joints, so both of the welding methods can be used for seal welding of stainless steel lap joint. Copper brazing has more beautiful appearance, more controllable weld shape, smaller welding heat input, and the microstructure, hardness distribution and corrosion resistance of copper brazing joint are superior to those of rapid short arc MAG welding. In conclusion, the comprehensive performance of copper brazing is better than that of MAG welding, and it is more suitable for seal welding.