Developing novel ceramic materials with excellent thermophysical properties is one of the hotspots in the field of thermal barrier coatings. The (Sm_0.2Gd_0.2Dy_0.2Y_0.2Yb_0.2)₃TaO₇ high-entropy ceramic was fabricated via high-temperature solid-state reaction. The crystal structure, microstructure, phase stability and thermophysical properties were investigated. Results indicate that (Sm_0.2Gd_0.2Dy_0.2Y_0.2Yb_0.2)₃TaO₇ high-entropy ceramic has single defective fluorite structure, its elements are homogenously distributed, its grain size ranges from 0.2 to 3 μm. After high-temperature thermal cycling, the sample still remains single fluorite structure, showing excelleent phase stability at high temperature. Thermal conductivity lies in the range of 0.72-0.74 W/(m·K), lower than that of 7YSZ. Thermal expansion coefficient at 1200 ℃ is 5.6×10^-6 K^-1, lower than requirement of thermal barrier coatings (TBCs) for surface ceramic layer. However, its thermal expansion coefficient is close to that of the silicon-based ceramics substrate of environmental barrier coatings (EBCs) ((3.4-5.5)×10^-6 K^-1).