A dense ZrB₂ particles reinforced glass (ZrB₂/SiO₂) coating was prepared on the SiC coated carbon/carbon composites by a facile sol-dipping approach. The prepared ZrB₂/SiO₂ coating could protect the composites from being oxidized for 160 h at 1773 K with a weight loss of 6.9 mg/cm². The flexural strength retention ratio of the ZrB₂/SiO₂ coated composites is 87% after oxidation for 160 h at 1773 K. The continuous SiO₂ glass layer embedded with the submicron ZrSiO₄ particles was formed during oxidation. This was helpful to lower the diffusion rate of oxygen and improve the stability of SiO₂ glass film, thus improving the oxidation resistance of the coated samples. After thermal cycles between 1773 K and room temperature for 15 times, penetrated cracks formed in the coating. The weight loss of the ZrB₂/SiO₂ coated sample presented linear relationship, and the final weight loss per unit area was 6.35 mg/cm². The generation of the penetrative cracks and the debonded coating interface resulted in the failure of the ZrB₂/SiO₂ coating.