Abstract: Using industrial grade sodium silicate as silicon source and water as reactant and solvent, SiO2 aerogels were prepared by two-step acid-base catalysis and dried at ambient pressure, 45 ℃. The aerogel structure and properties were characterized. The effects of ammonia concentration, time of hydrolysis, pH value on the gel time and the aerogel properties were studied. Results show that the prepared SiO2 aerogel had typical aerogel structure characteristics and high thermal insulation properties, with the pore size of 8-12 nm, the specific surface area of 353-613 m2·g-1, particle diameter of 10-20 nm, the density of 0.09-0.15 g·cm-3, the thermal conductivity of 0.021 08 W·m-1·K-1.