Abstract: In this paper, the self-maintaining arc in vacuum with hollow cathod and its application for welding and brazing were studied. The experimental results showed that for fusion welding, the vacuum arc is possessed of good stiffness, strong penetration and a good appearance of weld on both sides. The strength and plasticity of the joints welded by vacuum arc are much better than those of the joints welded by the traditional arc. And for brazing, the vacuum arc provides excellent flexibility, fast heating, easy controlling of parameters and high quality of brazed joints etc. As the duration at high temperature is very short, the harmful intermetallic compounds inside the joint could be avoided. Hollow cathod vacuum arc is a new kind of welding heat source which promises good prospect.