Silica　aerogels　from　wheat　husk　ash　(WHA)　were　prepared　via　a　sol-gel　process　by　ambient　pressure　drying.　Silica　was　extracted　from　WHA　by　NaOH　solution　to　form　sodium　silicate,　which　was　used　as　precursor　for　aerogels.　Silica　wet　gels　were　synthesized　by　resin-exchange-alkali-catalysis　of　the　sodium　silicate　solution,　followed　by　solvent　exchange　with　ethanol　(EtOH)　and　hexane　in　turn.　Consequently,　a　mixture　of　trimethylchlorosilane,　EtOH　and　hexane　was　used　for　surface　modification　of　the　wet　gels　in　order　to　obtain　hydrophobic　silica　aerogels.　The　density,　pore　structure,　hydrophobic　property　and　thermal　insulation　property　of　the　obtained　silica　aerogels　were　investigated　in　detail.　The　results　show　that　the　formation　of　silica　aerogels　can　be　successfully　realized　at　a　SiO2/H2O　weight　ratio　varying　from　0.065　to　0.167.　Silica　aerogels　possess　a　desirable　pore　structure　with　a　surface　area　ranging　from　513　+/-　A　5　to　587　+/-　A　6　m(2)/g,　a　pore　volume　from　2.3　+/-　A　0.3　to　4.0　+/-　A　0.1　cm(3)/g　and　a　pore　size　from　9　+/-　A　2　to　15　+/-　A　1　nm,　an　outstanding　hydrophobic　property　with　a　water　contact　angle　of　147　+/-　A　0.1A　degrees　and　a　distinguished　thermal　insulation　property　with　a　low　thermal　conductivity　ranging　from　0.009　+/-　A　0.0001　to　0.012　+/-　A　0.0002　W/(m　center　dot　K).