Abstract: The distribution of anode temperature during arc coupled AA-TIG welding was measured with the thermocouple method.In the vertical direction of connection line between the main and aided tungsten electrodes,the temperature gradually descended outward from the connection line.The maximum temperature appeared in the main electrode,and the minimum temperature occurred at the center between two electrodes.In the direction of the connection line of two electrodes,with the increase of the distance between two electrodes,the temperature in the central region of the coupled arc gradually decreased,while that in the outer region increased.The distribution of temperature transferred from single-peak mode to double-peak mode.When the distance between the main electrode and aided electrode was large,the arc heat source in the direction of connection line between two electrodes was stretched,which would help to eliminate undercut and humping defects during high speed welding.