With improvement in service temperature of thermal structural components for the new generation hypersonic aircraft, higher requirements are put forward for the phase stability and ablation resistance of the thermal protection coatings (TPCs). Carrying out high-entropy design for traditional transition metal oxide ZrO₂ and HfO₂ coatings, solid-phase reaction and supersonic atmosphere plasma spraying (SAPS) were applied to prepare (Hf_0.125Zr_0.125Sm_0.25Er_0.25Y_0.25)O_2-δ (M1R3O), (Hf_0.2Zr_0.2Sm_0.2Er_0.2Y_0.2)O_2-δ (M2R3O), (Hf_0.25Zr_0.25Sm_0.167Er_0.167Y_0.167)O_2-δ (M3R3O) high-entropy oxide (HEO) coatings. The effects of rare earth content on phase structure evolution, phase stability and ablative resistance of HEO coatings were investigated. M2R3O coating and M3R3O coating possessed excellent phase stability and ablation resistance, which maintained stable phase structure after ablation by oxygen-acetylene flame with heat flux density of 2.38-2.40 MW/m², without decomposition of solid solution and precipitation of rare earth components. Mass ablation rate and linear ablation rate of M2R3O coating after cyclic ablation for 180 s are 0.01 mg/s and -1.16 μm/s, respectively. Compared with M1R3O coating (0.09 mg/s, -1.34 μm/s) and M3R3O coating (0.02 mg/s, -4.51 μm/s), the reductions of ablation rate are 88.9%, 13.4%, respectively, and 50.0%, 74.3% for M2R3O coatings, respectively, presenting the best ablation resistance. M2R3O coating exhibits excellent ablation resistance due to its high melting point (>2200 ℃) and low thermal conductivity ((1.07±0.09) W/(m·K)), which effectively protects the internal SiC transition layer and C/C composites from oxidation damage, avoiding interface cracking caused by the formation of SiO₂ phase.