In order to develop a novel welding process with low costs and high productivity in comparison with the TIG welding process, the characteristics of a CO2 gas shielded gas tungsten arc (GTA) are studied. A double gas shielded system which consists of CO2 gas and inert gas is employed for the GTA welding torch due to avoiding the consumption of tungsten electrode. The arc voltage of the CO2 gas shielded GTA in the conditions of arc current 150 A and arc gap 3 mm is about 19 V which is much higher than 12 V of TIG arc in the same conditions. The CO2 gas clearly constricts the arc and the maximum heat intensity at the surface of a water cooled copper anode in the CO2 gas shielded GTA becomes about 10 times larger than that of TIG arc. Furthermore, the CO2 gas shielded GTA has very good performance in the traveling speed for welding zinc coated steel sheets in comparison with the TIG welding process.