Abstract: In view of the defects of small flexible pipeline with thin wall and slender structure during argon arc welding process, such as poor weld appearance, inner hole obstruction and oxidation, the clamping tooling for pipeline and ball head, welding structure and welding parameters were studied. By designing the clamping structure with clamping and pushing, controlling the assembly clearance and setting welding current in sections, the weld with uniform peneration, good appearance and no oxidation was obtained, and the weld quality meets the requirements of mechanical property, leakage rate, internal and external quality.