Abstract: The Al₂O₃/MoSi₂ coating on Al₂O₃ base porous insulation materials was prepared by brushing method. Silica sol served as binder and MoSi₂ as high emissivity component while nano Al₂O₃ and Al₂O₃ fiber were used as high temperature component. The surface morphology and crystalline structure of the Al₂O₃/MoSi₂ coating were analyzed by SEM and XRD. The effects of the mass ratio of nano Al₂O₃ to Al₂O₃ fiber and the content of MoSi₂ on thermal endurance of the Al₂O₃/MoSi₂ coating were studied. Thermal shock resistance and radiative property of the Al₂O₃/MoSi₂ coating were investigated. The results indicate that there is no cracks on the Al₂O₃/MoSi₂ coating surface when the mass ratio of nano Al₂O₃ to Al₂O₃ fiber is less than 1∶1. Fiber-network is relatively integrated on the Al₂O₃/MoSi₂ coating at the mass ratio of nano Al₂O₃ to Al₂O₃ fiber of 1∶2–1∶4. The best content of MoSi₂ in the Al₂O₃/MoSi₂ coating is 20%. When the content of MoSi₂ is 20%, the surface of Al₂O₃/MoSi₂ coating remains unbroken after 25 thermal shock cycles. The Al₂O₃/MoSi₂ coating has high emissivity which is around 0.85 at 2.5–25 μm after heat treatment.