The　high　frequency　current　pulse(≥20　kHz)　output　is　difficult　to　achieve　because　of　dynamic　characteristic　limit.　The　digital　control　TIG　welding　system　with　high　frequency　pulse　assembled　has　been　proposed　in　this　research.　This　system　adopts　novel　power　circuit　with　DSP　and　CPLD　control.　By　which　the　system　can　achieve　high　frequency　pulse　welding　according　to　special　scheduling　and　external　characteristic　control.　This　stable　welding　processing　can　decrease　the　number　of　blowholes　during　aluminum　alloy　welding,　increase　grain　refining　efficiency　and　improve　the　performance　of　welding　joint.　A　novel　high　quality　welding　heat　source　has　been　created.