Slica-alumina composite aerogels are prepared via introducing small amount of tetraethoxysilane (TEOS) during sol-gel process and then modified by partially hydrolyzed aluminum trisec butoxide (ASB) and TEOS during supercritical fluid drying with ethanol.The introduced TEOS produces small silica particles on alumina surface at high temperatures which inhibits the crystal growth upon heat treatment.The optimized composite aerogel has no crack and little shrinkage during aging and drying process, and shows no shrinkage and high specific surface area after heat treatment at 1200℃, which shows excellent heat resistance and formability.This may significantly contribute to their high-temperature applications such as thermal insulation, catalysts, catalyst supports.