Abstract: In order to improve welding quality, welding efficiency of pipeline shifting tie-in and reduce labor intensity, CPP900-W1A automatic welding with single welding gun pipeline was used for welding of pipeline shifting tie-in in the experiment. Double V-shaped groove was designed optimally by the test. Combined with results of phased array ultrasound testing (PAUT), radiographic testing (RT) and macroscopic metallographic morphology of weld defects, typical defects of welded joints were analyzed, construction methods and process methods were optimized, and welding efficiency verification and mechanical properties of welded joints were carried out. The experiment results showed that compared with single V-shaped groove, double-V groove reduced filling amount by about 30%. For adopting welding process of solid wire gas shielded downward welding (root welding, hot welding) and flux-cored wire gas shielded upward welding (fill welding, cover welding), welding time was 2.8~3.5 h. Compared with traditional welding process, it saved about 50% of welding time. The welding process was used to weld five joints continuously, welded joints were qualified by inspection, and mechanical properties of welded joints meet requirements of relevant standards. The construction method and welding process that satisfied pipeline shifting tie-in were obtained, which provided an efficient and reliable welding process for shifting tie-in of East China-Russia gas pipeline.