The hinged welding technology of HG785 D thin-walled grooved parts is researched and tested. A reasonable set of welding procedure specification for HG785 D sheet welding is analyzed and summarized. And it can reduce the complex and multiple deformations of thin-walled parts to achieve single-sided welding double-sided forming, and also can effectively solve the technical problems in thin-walled beam welding to ensure the one-time qualified rate of radiographic inspection for welds. And the mechanical property of welds is tested.