A series of PAM/silica nanocomposite (NC) gels using silica sol as the inorganic component were prepared by in situ free-radical polymerization. The addition of silica sol was first used to bring silica nanoparticles to form organic (polymer)/inorganic system. Results from the swelling experiment indicated that the effect of silica particle was nevertheless rather complex as polymer/particle binding. Additionally, it revealed that the swelling ratio of the NC gels with a certain silica content increased with the increasing pH value. Moreover, it exhibited absorption of the polymer onto silica because the chemical cross-linked PAM has changed to the organic/inorganic system. The spectroscopic results showed that the silica nanoparticles formed by silica sol promoted high degree of attachment to the polymer chain. The AFM micrographs displayed that silica particles were of nano degree and in the monodisperse. Both evidences proved that the organic/inorganic system was effectively formed through the addition of silica sol.