Based the characteristics of variable polarity TIG welding,a tiny current short arc ignition was designed,which solved the problem of tungsten weariness,especially when the state of DCEP（direct current electrode positive）. There are three stages of tiny current short arc ignition,the three stagers are short stage,maintain stage and current slow rising stage,and the current of the short stage can be only 2 ～3 A. The experiments proved that the arc ignition is stable without any obvious tungsten weariness and arc extinguish,and the arc ignition success rate is quite high.