Abstract: A two-dimensional axisymmetric model for Gas Pool Coupled Activating TIG welding is established based on the MHD theory and species conservation. Arc plasma coupled with cathode is numerically simulated by simplified cathode sheath model. By solving this model, the distributions of temperature, oxygen, current density and heat flux at anode surface under different outer layer gas flow and coupling degree are obtained. The results show that the arc of gas pool coupled activating TIG welding constricts, the velocity of plasma and arc pressure at anode surface increase compared with TIG arc under the same conditions. Increasing the flow rate of oxygen or the coupling degree, the maximum temperature of arc rises, the trend of oxygen diffuses into arc is more obvious, the welding arc constricts slightly, the peak values of current density and heat flux at anode surface all increase.