Abstract: Astudy has been made of ternary salt system BeSO₄-Al₂(SO₄)₃-Na₂SO₄ by the thermal analysis method. A ternary peritectic point containing BeSO₄ 18.8 Wt%, Al₂(SO₄)₃ 15.0%, Na₂O₄ 66.2%, melting at 490℃and a ternary eutectic point containing BeSO₄ 20.0%, Al₂(SO₄)₃ 11.2%, Na₂SO₄ 68.8%, melting at 475℃, were found in this system. The composition of the other ternary eutectic point melting at 595℃has not been exactly determined. No evidence was found about any ternary compound existing in the system.