Aiming at the low welding efficiency and defects such as undercut and hump in the tungsten inert gas welding（TIG） of pure titanium TA2 thin walled pipe,the tandem TIG welding process is proposed,which can effectively increase the welding speed and improve the appearance of weld. The ABAQUS software is used to build welding thermal elastic-plastic finite element model for the two kinds of welding methods,and the welding temperature field and residual stress field are compared and analyzed. The microstructure analysis and mechanical properties test of welded joints are carried out. The results show that the weld contour sizes of the two simulated joints are similar to the actual joint and the weld center temperature of tandem TIG is lower than that of TIG. The width of Von Mises stress range above 200 MPa around tandem TIG is less than that of TIG,and the values of Von Mises stress in weld center are similar. The microstructure of the weld center and HAZ of tandem TIG is smaller than that of TIG,and the mechanical properties and corrosion resistance of the two joints meet the requirements of relevant standards.Under the conditions that the pure titanium TA2 pipe with a specification of Φ19 mm×0.7 mm obtains good appearance of weld,the welding speed by tandem TIG welding can reach 5 m/min. Comparing with TIG,the tandem TIG welding can highly improve production efficiency and basically accomplish no defect of straight weld.