Abstract: The sol was prepared by hydrolyzed tetraethoxysilane (TEOS) .The solid content of the sol is 23.6%, and the viscosity is 20s after 48h.The gel was characterized by XRD and infrared spectroscopy in this paper.The examination results of infrared spectra show there is a characteristic antisymmetric stretching vibration absorption peak of Si—O—Si at 1087.8cm^-1.X-ray analysis indicates that the gel is noncrystal SiO₂.The method of producing SiO₂ gel/wood composite compound with sol prepared at first and then impregnating sol into the wood issue by negative-positive pressure system overcomes its slow and incomplete defects in hydrolysis-condensation process compared to the former method of impregnating TEOS into the wood issue directly and then forming the sol, and the weight of percentage gain can reach 81.3%.