Abstract: To further enhance the high deposition efficiency advantage of wire and arc additive manufacturing, a new technology and method using a two TIG activating arc as the heat source was proposed. By introducing a small amount of activating gas O₂ into the argon shielding gas, a thin-wall deposition experiment were conducted and fabricated using 1.2 mm diameter SUS304 austenitic stainless steel metal wire. The effects of oxygen added, deposition current distribution, arc travel speed, and wire feed speed on the average width and height of the deposited bead were studied. The microstructure and mechanical properties of the deposited components were also examined. The results indicate that, compared to the conventional TIG method, the two TIG activating arc additive manufacturing not only improves forming and increases deposition efficiency but also reduces the surface tension of the deposited metal and the molten pool, enhancing their wettability and spreading characteristics, thereby further improving the deposition layer formation. Under comparable current conditions, the deposition efficiency is significantly increased, reaching 2.7 kg/h, compared to the conventional TIG arc deposition. As the deposition current of the trailing torch increases (the leading torch deposition current decreases), the average width first increases and then decreases, while the average height shows an opposite trend. With the increase in arc travel speed, both the average width and height decrease. When the wire feed speed increases, the wall height significantly increases, while the width changes little. The introduction of O₂ has no significant impact on the microstructure of the deposited thin-wall component, which is characterized by columnar dendrites perpendicular to the deposition direction. The tensile strength and elongation rate of the deposited thin-wall slightly decrease with the introduction of O₂.