The polystyrene-silica hybrid materials have been successfully prepared from styrene and tetraethoxysilane in the presence of silane-coupling agents by an in situ sol-gel process. Triethoxysilyl group can be incorporated into polystyrene as side chains by the free-radical copolymerization of polystyrene with silane-coupling agents, and simultaneously polystyrene-silica hybrid materials with covalent bonds between two phases were formed via the sol-gel reaction. The 3-(trimethoxysilyl)-propyl-methacrylate (MPS) systems were found to be more homogeneous than the corresponding allytrimethoxysilane hybrid system of equal molar content. In the MPS-introduced system, the thermal properties of the materials were greatly affected by the presence of MPS. FTIR results indicate successful formation of the silica networks and covalent bonding formation of coupling agents with styrene. The homogeneity of polystyrene-silica systems was examined by scanning electron microscope and atomic force microscope.