Ethylene-modified　microporous　silica　membranes　were　prepared　by　acid　catalysed　cohydrolysis　and　condensation　reaction　of　tetraethylorthosilicate(TEOS)　and　ethylenetriethoxysilane　(TEVS)　in　ethanol　and　characterized　by　means　of　N-2　adsorption,　TG,　NMR　and　contact　angle　meter.　The　results　show　that　the　modified　materials　remain　a　desirable　microporous　structure　with　a　pore　width　centered　at　0.5-0.7nm,　and　that　the　hydrophobic　property　of　modified　silica　membranes　is　considerably　improved　due　to　the　gradual　replacement　of　hydrophilic　silanol　by　hydrophobic　ethylene　on　the　surface　with　increasing　molar　ratio　of　TEVS/TEOS.