Transparent glass cloth reinforced composite films were fabricated by ultraviolet (UV) light which induced chemical crosslinking of composite materials consisting of glass cloth and UV curable resin in film state. UV curable resin has been recognized to be the general trend of transparent glass cloth reinforced plastic (GCRP) resins because of its excellent heat resistance and chemical stability resulted from the dense network structure by UV curing of oligomers and monomers. But when GCRP is fabricated by UV curing of matrix resin, there exist three different refractive indices from cured resin, uncured resin, and glass cloth. To minimize uncured matrix resin and improve the transmittance of GCRP, the composite films were treated by heat after UV curing. As a result of heat treatment, optical properties of the composite films were enhanced and the excellent thermal and dimensional stability at the high temperature more than 300 A degrees C were achieved.