Abstract: Five self-shielded flux cored wires with different fluxes were fabricated. The effect of different BaF₂ and CaF₂ mixture ratio on welding technology, transition droplet and P,Si controlling in the deposited metal was studied. The result shows that with the increasing of BaF₂, the spatter loss,smoke, and the average diameter of droplet at 50% mass percent as well as the deposition efficiency and ratio of maxmun penetration and maxmum weld width decrease. And the vertical welding ability is improved. BaF₂ has more powerful capability than CaF₂ to control the P and Si in the deposited metal. The controlling mechanism is explained by thermodynamics analysis. In the view of welding technology and P,Si controlling in the deposited metal, the range of 75~87.5% BaF₂ of the total fluoride in the flux is preferred.