Copper has excellent electric conductivity, heat conductivity, corrosion resistance, malleability and certain intensity. Widely used in the industry of electric, electronic, chemical, food, power, traffic and aerospace. Four elements are in the technology difficulty of copper welding-Firstly, high thermal conductivity influence. Secondly, large hot tearing tendency of welded joint. Thirdly, generated gas holes defect is much more serious than carbon steel defect. Fourthly, welded joint property transformation.