Abstract: A new activating TIG welding process for stainless steels called AA-TIG(arc assisted activating TIG) welding is proposed.The weld surface is pre-melted by low current tungsten arc with activating mixing shielding gas before normal TIG welding, which can dramatically improve weld penetration and production efficiency and ensure the repeatability of welding process and automatic welding. O₂+Ar, CO₂+Ar and air are respectively used as the shielding gas of pre-melting with low current tungsten electrode arc for single-arc AA-TIG welding;compared with conventional TIG welding, all of the three mixing gases can increase weld penetration and decrease weld width;all of the weld appearances are fine.When CO₂+Ar mixing gas is used as the shielding gas of low current tungsten electrode arc in dual-arc AA-TIG welding, the weld forming is fine, the weld penetration is improved dramatically, but the weld penetration increases as the distance between the welding torches decreases.