Abstract: The butt welding of 10 mm thick Gr.12 titanium alloy test plate was welded by using K-TIG welding with filler wire, and the welded joint with good weld quality was obtained. The macroscopic morphology and microstructure of the welded joint were observed, and the mechanical properties of the welded joint were tested. The results show that weld width is large, the grains of the weld zone is coarse, lath martensite α’ phases with different orientations are distributed in the grains,while the dot β phases are distributed between the lath martensite α’ phases. The average tensile strength of the joint is 568.5MPa, the tensile specimens are broken in the parent metal. The bending property of the welded joint is good.