Abstract: This paper introduces the twin electrode single arc welding technology. Twin electrode single arc welding is that work-piece does not link power source, electric arc is ignited and burned between mutual insulation welding rod. The igniting and combustion of electric arc can go on in the space away from work-piece in different distance. The space between two cores of twin electrode is the key factor to control arc voltage. Adjusting the space between two cores of twin electrode and work-piece has very little influence on arc voltage. Arc voltage goes up when welding current increases. Using twin electrode of 45.6% coating weight coefficient, with φ4 diameter,under the condition that the space between two cores is 1.2~1.7mm and welding current is 180~220A, joints that have welded appearance and mechanical property can be gained.