Abstract: A new activating welding process, arc assisted activating TIG welding (AA-TIG welding), is put forward.The effects of welding parameters on weld penetration and width are studied using SUS304 stainless steel as base metal.The results indicate that the weld penetration of AA-TIG welding can increase above 2 times of that of the traditional TIG welding in the same welding conditions and the weld width reduce dramatically.Using AA-TIG welding process, the 8mm thickness stainless steel can be fully penetrated without making a groove.Welding efficiency is obviously improved. Welding specifications of the assisted arc and common TIG welding have influence on the weld penetration and width of AA-TIG welding.