Abstract: Several single common compounds were taken as basic activating fluxes in the tungsten inert gas (TIG)welding process with filler wire.The results indicated that in A-TIG welding of magnesium alley, the activating fluxes coated on the welding wire can also increase weld penetration.The chloride shows a prominent effect on the weld penetration, and the penetration even can be increased 3 times, which compared with the conventional TIG welding with filler wire.The boiling points of the fluxes that increased weld penetration are mostly in the regions about 900℃.The interfusion ability between the droplet metal and the weld pool metal became worse in the TIG welding process with filling activating welding wire than that with the normal wire, and filling ability of the welding wire deteriorates a little, comparing with the normal welding mire.