This study has been carried out to investigate into the dephosphorization by using fluxes containing Na₂CO₃-CaF₂-Na₂B₄O_7., l0H₂O and CaO-CaF₂-Na₂B₄O_7. 10H₂O system in molten bronze alloy. The dephosphorization degree of about 80% and 70% were obtained by Na₂CO₃-CaF₂-Na₂B₄O_7. 10H₂O and CaO-CaF₂-Na₂B₄O_7. 10H₂O system, respectively. When the contents of phosphorous in the molten bronze alloy were kept constant, although the amounts of fluxes exceed a given amount, it showed to give little effect in the degree of dephosphorization. The effects of dephosphorization in the molten bronze alloy was increased proportionally with increasing the contents of both phosphorous and amounts of fluxes. The slag formed from the Na₂CO₃-CaF₂-Na₂B₄O_7. 10H₂O system was found to be NaCaPO₄, Na₄P₂O_7 and NaF. The slag of CaO-CaF₂-Na₂B₄O_7. 10H₂O system was composed of Ca_5F (PO₄)3, CaO and CaF₂.