The Sol-Gel (S-G) method is a moderate temperature process for prepa ring nanomaterials. In this paper, we discuss the principle of the S-G method, problems associated with it, as well as the hydrolysis characteristics of inor ganic compounds and metal alkoxides. By way of case study we consider the S-G p rocessing SnO2. We also go on to consider the future of the S-G method.