Abstract: Titanium and its alloys have the characteristics of low density, high strength, good corrosion resistance, and widely applied in aviation, aerospace, chemical machinery industries and other industries. In the construction of the titanium alloys tube, if the tube diameter is small (ϕ20～100 mm), the difficulty of welding construction will increase. In order to improve the welding quality of small diameter titanium alloys tube and prevent the blowhole from welding, the preparation of welding environment, material and preventive measures during welding were introduced, and the methods of welding quality inspection were also expounded.