A certain transformer support is made of Q235 B steel tube. In order to achieve the requirements of preventing eddy current phenomenon and special performance,it is necessary to use red copper for filling and welding. The welding of steel and copper is difficult,welded joint is prone to hot crack and porosity defect. By analyzing their weldabilities and welding process problems,it is decided to adopt the manual tungsten argon arc welding（GTAW）. By making a reasonable welding procedure,including the controls of welding materials control,welding procedure measures,welding parameters,welding operations,the welded joint obtained meets the requirements of quality and design.