Abstract: Aiming at the problems of weld-through, undercutting and unfused welding of the bottoming layer in flat welding position in all-position welding of pipelines, a narrow bevel flat welding position welding process method based on rotating arc was proposed. Taking X65 pipeline steel plate butt narrow bevel as the test object, based on Minitab’s Taguchi method, an orthogonal test model was established to investigate the influence of different combinations of process parameters on weld shaping under the rotating arc STT flat welding bottoming welding program. The results show that when the welding process parameters are the wire feeding speed of 6.2 m/min, welding speed of 26 cm/min, rotating speed of 1200 r/min, the rotating arc STT flat welding bottoming single-sided welding double-sided molding consistency is good, there are no welding defects, which can lay a foundation for the development of the basic process specification for the pipeline all-position welding flat welding position