A silicon sol-gel was prepared by tetraethyl orthosilicate(TEOS) as precursor of sol-gel process under acid or alkaline catalysis.The influences of ethanol or water contents were investigated on sol-gel process under acid or alkaline condition.The structure of silicon sol-gel was characterized by FT-IR and SEM methods.The results showed that the optimal materiel ratio was obtained when molar ratio of n(ethanol)∶n(TEOS) was 2∶1 under acid condition or 4∶1 under alkaline condition,and molar ratio of n(TEOS)∶n(water) was 1∶2.The liquid silicon sol-gel which was prepared under acid condition had linetype structure and more homogeneous systems,but the liquid silicon sol-gel which was prepared under alkaline condition had dimensional structure and unhomogeneous systems with particle-congeries.