Abstract: As one of the most common A-TIG welding activating fluxes, fluorides have been widely used in actual welding production, but its influence mechanism on arc behavior is still controversial. To this end, the spectral diagnosis method was used to study the spatial spectral distribution of the A-TIG welding arc coated with fluoride flux, the distribution characteristics of flux particles, argon and iron particles in the arc space were analyzed, and the Boltzmann diagram method was used to calculate arc electron temperature. The experimental results shown that the flux particles are mainly distributed in the central area of the arc column; fluoride can reduce the intensity of the ArⅡspectrum in the arc and increase the intensity of the FeⅡspectrum; the effect of fluoride on the temperature of different arc regions is not consistent. Among them, the arc temperature near the anode area is greatly increased, but the effect on the arc temperature in other areas is small.