Abstract: According to the high flatness requirement of a specific aluminum component, the direct current activating TIG welding (DC A-TIG) has been realized by using a self-developed activating flux. The appearance, internal qualities, microstructures and mechanical properties of the DC A-TIG welds have been studied. The results indicate that when the activating flux concentration is 15%, a 2A14 DC A-TIG weld with good appearance, internal quality and mechanical property can be obtained. Comparing to the alternating current TIG (AC TIG) welds, the mechanical properties of the DC A-TIG welds are a little higher and the number of the micro porosities decreases dramatically.