Abstract: The welding technology of thin sheet of aluminium alloy is studied by using the double inverter pulsed AC TIG welding power source in this paper.The influences of pulsed current peak value,EP time and pulsed current frequency on the welding technology are studied.The pulsed current peak value and EP time have a important effect on removal of the surface oxide,the lower frequency should be adopted for thin sheet of aluminium alloy.With rational welding parameters,the welding appearance can be easily controled,and the good welding quality can be acquired.