To improve oxidation resistance of carbon/carbon(C/C) composites,a SiC/SiC-MoSi_2-ZrB_2 double-layer ceramic coating was prepared on C/C composites by two-step pack cementation.The phase compositions and microstructures of as-prepared multilayer coating were characterized by X-ray diffraction and scanning electron microscopy.The oxidation resistance at 1773 K and the effect of thermal shock between 1773 K and room temperature on mechanical performance of coated specimens were investigated.The results show that the SiC/SiC-MoSi_2-ZrB_2 coating exhibits dense structure and is composed of SiC,Si,MoSi_2 and ZrB_2·It can protect C/C composites from oxidation at 1773 K for more than 510 h with weight loss of 0.5%.The excellent anti-oxidation performance of the coating is due to the formation of SiO_2-ZrSiO_4 complex glassy film.The coating can also endure the thermal shocks between 1773 K and room temperature for 20 times with residual flexural strength of 86.1%. To improve the oxidation resistance of carbon / carbon (C / C) composites, a SiC / SiC-MoSi_2-ZrB_2 double-layer ceramic coating was prepared on C / C composites by two-step pack cementation.The phase compositions and microstructures of as- prepared multilayer coating were characterized by X-ray diffraction and scanning electron microscopy. The oxidation resistance at 1773 K and the effect of thermal shock between 1773 K and room temperature on mechanical performance of coated specimens were investigated. The results show that the SiC / SiC The SiO 2 -ZrB 2 coating exhibits dense structure and is composed of SiC, Si, MoSi_2 and ZrB_2 · It can protect C / C composites from oxidation at 1773 K for more than 510 h with weight loss of 0.5%. The excellent anti-oxidation performance of the coating is due to the formation of SiO_2-ZrSiO_4 complex glassy film. The coating can also endure the thermal shocks between 1773 K and room temperature for 20 times with residual flexural strength of 86.1%.