In this article, the gelation behavior and gel structure were analyzed for the coating solutions of TEOS(tetraethyl orthosilicate)/VTES(vinyltriethoxysilane) with various molar ratios at different temperatures. Gelation was accomplished through the sol-gel method in aqueous solution. The gelation time and gel structure proceeded by the SEM, UV, NMR, rheometry, and visual observation. The gelation time was increased, but not linearly, with the content of the silane coupling agent VTES. Meanwhile, the gelation time was reduced with temperature. As the content of VTES was increased, the pore size of the prepared gel was increased. For example, when the VTES content was nine times as high as the TEOS content, the gel possessed large pores with low density structure. Moreover, in the latter case, the volume contraction was negligible with a considerably long aging time, which was different from the cases for other molar ratios. The present results showed that the post-treatment conditions in the sol-gel process affected the gel structure significantly.