Abstract: A mesoporous SiO2 aerogel was synthesized by using a surfactant-assisted templating sol-gel technique through graded ambient pressure drying. The effects of surfactants on the microstructure， thermal conductivity， and thermal stability of the as-synthesized SiO2 aerogel were investigated. The results indicated that the introduction of surfactants not only could avoid the solvent exchange process in the conventional sol-gel method but also could regulate the porous structure of the SiO2 aerogel. The SiO2 aerogel exhibited a low thermal conductivity of 0.018~0.035 W m-1 K-1， a high specific surface area of 469.56~692.07 m2/g， and good hydrophobicity with a contact angle of 136.7 °~151.8 °. This study provides an effective method for low-cost preparation of SiO2 aerogel with excellent performance， and the resultant aerogel can be used as thermal insulation and heat preservation materials in the building and industrial fields.

Key words: surfactant-assisted, SiO2 aerogel, ambient pressure drying, low thermal conductivity