Abstract: A new welding method was proposed innovatively for joining 2219 aluminum alloy. The welding surface was coated with a thin layer of activating flux with a function of removing the oxide film and gas before welding. And direct current straight polarity TIG welding method of 2219 aluminum alloy was obtained. This paper investigated the effect of activating flux concentration on the weld surface appearance, porosity defect, microstructure and mechanical properties of 2219 aluminum alloy joints by direct current straight polarity A-TIG welding. The results showed that the 2219 aluminum joint with pore-free, sound surface appearance and excellent mechanical properties was obtained when the activating flux concentration was up to 10%. Compared with the variable polarity TIG welding, direct current straight polarity A-TIG welding presented better arc stability, less heat input, more excellent welding quality.