Abstract: In order to study the coupling arc AA-TIG (arc assisted activating tungsten inert gas) welding,a static keyhole method was used to measure the arc pressure with stainless steel as the anode. The influence of main process parameters on the distribution of arc pressure was analyzed. Compared to the conventional TIG welding process under the same conditions,the peak value of arc pressure during the coupling arc AA-TIG welding was significantly reduced. With the welding current decreasing, the electrode distance increasing,the arc length increasing and the oxygen content of the assisted arc decreasing,the peak value of arc pressure in coupling AA-TIG welding decreased. The distribution of arc pressure was in concordance with Gaussian distribution at 2 mm electrode distance. With the electrode distance increasing,the distribution gradually turned into bimodal distribution.