Abstract: The weld formation of twin-electrode tungsten inert gas (T-TIG)welding was studied with numerical simulation.With a view to the arc deflection from the mutual attraction between the two arcs, inclined heat source model was adopted.The weld formation features of T-TIG and traditional TIG were comparatively analyzed. The effects of electrode distance, the current value and the matching of currents on the shape of melting pool were studied.The results show that compared with single-electrode tungsten inert gas, the weld width of T-TIG is narrower, and the weld depth is little smaller;with the increasing of electrode distance, the weld width increases, the weld depth decreases;With the increase of currents, the weld depth and width both increase;the current matching forms between electrodes also have certain influences on the weld formation.