Abstract: The effect of welding currents and welding speed on bead appearance and shape of triple-electrode high speed CO₂ fillet welding on double sides was investigated.It was found that the current of leading electrode should be the highest,and current difference between leading electrode and middle electrode had better be 100A or above to obtain good weld quality.The current difference between middle electrode and trailing electrode don't play an obvious role in weld quality,and the electrode offset should be at flat plate.Welding process stability was analyzed through current and voltage acquisition signals characteristic parameters on Lab VIEW and high speed photograph.It indicated that the voltage fluctuation increased with the increment of welding speed,the fluctuation by 400/300/300A combination is the lowest at the same welding speed,and the inter-wire distance should be increase to decrease the arc interference.