Abstract: Choosing 6082-T6 aluminum alloy as research object, which is the major material used in pantograph, gas tungsten arc welding(GTAW) was used to weld the alloy at different shielding gases. The effects of different shielding gases on microstructure and mechanical properties of welded joints were studied. The results show that, the weld seams had some microstructure at different shielding gases, and their microstructure were all equiaxed grains, and the microstructure of fusion zones were columnar zone. With the ratio of helium in mixed gas decreasing, the grains in the weld seams and fusion zones get coarse and the strength of the welded joints dramatically decreased. The welded joint exhibited the highest tensile strength of 182 MPa when the shielding gas was composed of 50%Ar and 50%He, the width of heat affected zone was maximum and its softing was serious when the shielding gas was 100%Ar.