Abstract: The wet gel has been treated by cationic surfactant of dodecyltrimethylammonium bromide（DTAB） aqueous solution，so that the liquid surface tension can be reduced in the wet gel and the silica aerogel with intact pore structure can be obtained.Results showed that the method of using DTAB solution to soak wet gel is better than the method of adding DTAB before the forming of wet gel.The test parameters of silica aerogel were as follows: porosity of 81.8%，average pore size of 15.749 nm，total pore volume of 2.836 cm³/g，and specific surface area of 923 m²/g，when the wet gel was soaked in 1.48× 10^-2 mol/L DTAB aqueous solution；the adsorption and desorption curve was obviously higher than that of other concentrations of DTAB，exhibiting strong adsorptivity；the pore structure can be observed clearly from the TEM photogaphy；and the silica aerogel after being treated by DTAB was significantly better than those without treatment.

Key words: surfactant, silica aerogel, dodecyltrimethylammonium bromide