Abstract: Binary system samples and Ta₂O₅-WO₃-RO₂ (R=Zr,Ti) ternary system samples were prepared after holding at 1 200℃ for 18 h with Ta₂O₅, WO₃, ZrO₂ and TiO₂ as raw materials. The phase composition was analyzed and the subsolidus phase diagrams of the Ta₂O₅-WO₃-RO₂ ternary systems at 1 200℃ were obtained according to the interaction and coexistence of each phase. The results show that five compounds of Ta₂₂W₄O₆₇, Ta₂WO₈, Ta₁₆W₁₈O₉₄, TiTa₂O₇ and TaZr_2.75O₈ were produced when the binary systems composed of Ta₂O₅, WO₃, ZrO₂ and TiO₂ were heated at 1 200℃ for 18 h. Four Coexisting triangles of Ta₁₆W₁₈O₉₄-WO₃-TiO₂, Ta₂WO₈-Ta₁₆W₁₈O₉₄-TiO₂, Ta₂WO₈-TiTa₂O₇-TiO₂ and Ta₂WO₈-TiTa₂O₇-Ta₂₂W₄O₆₇ and a solid solution region of Ta₂O₅, WO₃ and TiO₂ existed in the Ta₂O₅-WO₃-TiO₂ ternary subsolid system. Four coexistence triangles of Ta₂WO₈-Ta₂₂W₄O₆₇-TaZr_2.75O₈, Ta₂WO₈-Ta₁₆W₁₈O₉₄-TaZr_2.75O₈, WO₃-Ta₁₆W₁₈O₉₄-TaZr_2.75O₈ and WO₃-ZrO₂-TaZr_2.75O₈ and a solid solution region of Ta₂O₅, WO₃ and ZrO₂ existed in the Ta₂O₅-WO₃-ZrO₂ ternary subsolid system.