Abstract: The procedure qualification of activating TIG welding of monel alloy 400 is introduced in this paper. With the procedure,the squar butt joints of the plates 6mm and 10mm in thickness were welded by one side and by both sides separately.Metalloyraphic examination and mechanical property tests had been conducted on the joints. It is found that with the activating TIG welding,the penetration is deepened,the mechenical properties of the joints are fine and the welding material is economized.