Abstract: The twin electrode single arc welding is a new welding technology. The static characteristic of arc and melt property of twin electrode were studied, and the arc shape of twin-electrode single arc welding is observed with high speed camera. Rusults show that the arc static characteristic of twin electrode single arc welding is rising, the static characteristic curve goes up with the increase of the space between two cores. Under the right space between two cores, the melt rate of two core of twin electrode can keep consistent, so DC or AC power source can be used by the twin electode single arc welding. The melt rate of twin-electrode is bigger than single core electrode and increases with the increase of welding current and the decrease of space between two cores. The electric arc of twin electrode single arc welding have various forms.