Fourier Transform Infrared Spectroscopy (FTIR) was utilized to study the structure of the silane coupling agent and to identify graft copolymerization of monomer with three kinds of silane coupling agents on mica. Infrared spectra of mica alone and the treated mica with 5wt% vinyl silane aqueous solution were compared by FT-digital subtraction technique. Spectrum difference of polyvinylsiloxane solid indicated that the coupling agent on the mica surface took silane form. It was also found that silane coupling agent with viny1 functional groups on the mica surface could copolymerized with methyl methacrylate and styrene with radical initiators such as BPO and AIBN Grafting ratio and efficiency with BPO were higher than those with AIBN.