Abstract: In order to research the effect of welding gun tilt angle and the electrode inter-distance on coupling arc and weld formation for the tandem TIG welding of 1.24 mm thick titanium, this paper illustrated the mechanism of weld defect formation and inhibition, analysing the arc shape, current and voltage waveform by high-speed photography and electrical signal acquisition system.Experimental results showed that small arc interference and satisfactory bead formation were gained when the electrode inter-distance was between 11~15 mm. Beause of the back flow liquid metal suppressed, undercut was not found when the two guns distributed symmetrically. By using reasonable process parameters for the butt welding, the welding speed reached 3 m/min and the joint tensile sample fractured in the base metal with 434 MPa tensile strength and 31.4% elongation.