As for the investigation of the radiative properties for tungsten inert gas (TIG) welding arcs, the net emission coefficients are calculated for argon plasma in the temperature range of 5000-25000 K. A two-dimensional steady TIG arc-tungsten electrode -water-cooled cooper model is established to obtain the arc radiation intensity distribution, the full arc spectrum, and the radiation power of non-vacuum ultraviolet spectrum. A parameter defined as the ratio of radiation intensity to the sum of radiation intensity and ohmic heat is introduced and through the analysis of the distribution of this coefficient in arcs, it is found that the radiation plays a predominant role in the heat loss from arc body area, while the role of heat transport in the energy balance varies with the arc position.