Abstract: In this paper, a new method to produce hydropbic silica aerogels was introduced. SiO2 alcogels were prepared by tetraethoxysilane (TEOS) via two-step acid-base sol-gel process,then the solvent was exchanged and surface was modified by ethanol/hexmethyldisilazane/hexane, and finally dried at ambient pressure. The structure，appearance and properties of the silica aerogels have been investigated by FTIR, XRD, TG-DSC,F-SEM, BET. The results showed that one-step solvent exchane and surface modification process can reduce the time from 6 days to 3 days , the aerogels have high surface area,can be as high as 842.63m2/g. The density of the aerogels is low(130kg/m3),the diameter of particle size is about 15nm.the diameter of the pore sizes is in the range of 2-150 nm.The aerogels show an excellent hydrophobic feature.