Looseness,vibration,construction defect,discharge,overheating,and so on may occur glow phenomenon in copper connection under the long-term use. Recently,glow phenomenon occurred at car and copier. In this paper,we study process and characteristics of glow phenomenon using high speed camera, memory recorder,simulator,and so on. It is clarified that the mechanism of glow phenomenon in AC power under condition on glowing path,wa veforms of hot zone,and,similarity of glowing path and arc discharge.