Abstract: Active flux for austenitic stainless steel TIG(tungsten inert-gas) welding was studied using the orthogonal method.With the resulting flux and heat input of 1.01 kJ/mm,the austenitic stainless steel of 5 mm thickness was penetrated by TIG welding without beveling.When increasing heat input to 1.95 kJ/mm,the steel of 8mm thickness was penetrated.The arc was steady during welding,and appearance of weld is good.The flux has a function of suppressing alloy elements to escape from weld pool,so that the weight percentages of Cr and Ni in the A-TIG(active-tungsten inert-gas welding) weld metal are descended very slightly.The microstructure of the A-TIG welds is almost the same as that of the TIG welds.The hardness of the former is somewhate higher than that of the later.