ZrB₂-SiC and La₂O₃ modified ZrB₂-SiC coated C/C composites were prepared by high temperature reactive infiltration process. The oxidation resistance of the two coated samples in three temperature ranges, i.e. medium temperature (700-1100℃), high temperature (1200-1500℃) and super high temperature (over 2000℃), was compared. The results show that the oxidation resistance of La₂O₃ modified coatings increases gradually with the increase of temperature in the range of 700-1100 C. The coating exhibited good long-term oxidation resistance in the range of 1200-1500℃. The weight loss rate of ZrB₂-SiC modified by La₂O₃ was only 0.6% after 250 h oxidation at 1200℃ and 550 h oxidation at 1500℃. This is mainly due to the synergistic effect of La-Si-O composite glass layer and pinning phase ZrSiO₄ formed on the surface of the coating during oxidation, which improves the high temperature stability of the oxide film. The mass and linear ablation rates of ZrB₂-SiC coatings were reduced by nearly 50% with the addition of La₂O₃ under the flame ablation environment of acetylene and oxygen above 2000℃.