Ultra-low density SiO₂ aerogel as a classic three-dimensional network nano-porous material is widely used in many fields such as thermal insulation and adsorption. In this manuscript, tetramethoxysilane (TMOS) is used as the silicon source and an acid-base two-step method is used. Ultra-low density SiO₂ aerogels were prepared by ethanol supercritical drying technology, and a series of studies were performed on the aerogels using SEM\TEM\BET and other characterization methods. When the aerogel density was 0.6 mg/cm³, it had the best comprehensive properties. In addition, this aerogel has the advantages of ultra-low density, high specific surface area, good formability, and short preparation cycle. Thus, it is expected to play a significant role as a frozen target in laser inertial confinement fusion experiments.