With the polycondensates of methyltrimethoxysilane（MTMS）as film forming materials，the silica sol［hydrolysis products of tetraethylorthosilicate（TEOS）］surface-modified by 3-（methacryloxypropyl）-trimethoxysilane（MEMO）as an inorganic reinforcing material，the transparent organic-inorganic hybrid film on polycarbonate（PC）was prepared by the co-condensation reaction between hydroxy groups.The effects of the silica sol modified by MEMO on the properties and structure of the hybrid films were studied with TG/DTA，FTIR，UV-vis and metallographic microscope.The results showed that the cross-linked inorganic structure end-capped with organic groups formed on PC by the co-condensation reaction between hydrolysis products of MTMS and TEOS，whose base backbone was Si—O—Si network structure.At 150—250℃，thermally-initiated polymerization of C =C was observed and the hybrid film became more flexible with increase of MEMO.The film increased the transparency of PC while MEMO modification had little effect on its transparency.The film can obviously improve the hardness of PC，and the addition of MEMO can increase the thickness of film and make the film less liable to crack.