SiO₂ aerogel insulation composites were prepared by using ceramic fibers as reinforcement via supercritical drying process. Due to the ultra fine skeleton particles and nano-porous structure, silica aerogels have low gas thermal conductivity and solid thermal conductivity, and ceramic fibers greatly decrease radioactive thermal conductivity. Silica aerogel composites show excellent thermal insulation properties. The thermal conductivities at 200℃ and 800℃ are only 0.017W/m?K and 0.042W/m?K, respectively. The strength of the aerogel skeleton is enhanced by high temperature heat treatment, and with the reinforcement of fibers, the aerogel composites exhibit good mechanical property. The tensile, bending and compressive strengths at ambient temperature are 1.44MPa, 1.31MPa and 0.98MPa (10%strain), respectively, and the tensile, bending and compressive strengths at 800℃ are 1.95MPa, 1.80MPa and 1.42MPa (10%strain), respectively.