Abstract: The welding application of AC and DC pulse TIG in thin wall copper pipe was studied in the paper. Based on the analysis of AC and DC pulse welding current,the method of welding backing layer by DC pulse TIG and welding cosmetic layer by AC pulse TIG was proposed. This method not only guaranteed one side welding with back of backing weld of thin wall copper pipe,but also ensured it not produce overlap because of the excess temperature in cosmetic layer welding. After welding,welds of thin walled copper pipe were inspected. The X-ray film showed that the weld quality by the welding method was Class I,and results of mechanical properties test and metallographic test were also qualified. This provided a reference for improving the welding quality of thin walled copper pipe in the ship’s products.