NOVELTY - Preparing a transparent substrate, comprises: preparing a phenoxy resin composition comprising phenoxy resin (I), an energy-ray curable acrylic oligomer or acrylic polymer resin, a photoinitiator consisting of benzophenone, acetophenone, dibenzyl, diacetyl, diphenyl sulfide and/or azobisisobutyronitrile, and a crosslinking agent consisting of melamine, urea-formaldehyde, isocyanate functional prepolymer, a phenolic curing agent, and/or an amino-group curing agent; and (b) forming the phenoxy resin composition into a film or sheet by a solvent casting or melt extrusion method.    USE - The method is useful for preparing a transparent substrate such as a flexible plastic substrate and a glass substrate used in an optical device substrate, a flat panel display (FPD) substrate, a color filter substrate, a substrate for touch screen panel, and a substrate for solar cell, where the FPD substrate is a thin film transistor substrate for LCD or organic electroluminescent display (all claimed).    ADVANTAGE - The method is capable of easily and economically preparing the thin transparent substrate with excellent thermal resistance and chemical resistance, high adhesiveness, low water infiltration, small coefficient of linear thermal expansion, light-weight, improved flexibility and transparency, good surface flatness and low water and oxygen permeability and without structural limits. The transparent substrate is capable of effectively substituting for the conventional glass substrate. The phenoxy resin composition exhibits improved dimensional stability, rigidity and durability, and high barrier property and visible light transmittance.    DETAILED DESCRIPTION - Preparing a transparent substrate, comprises: preparing a phenoxy resin composition comprising phenoxy resin of formula (I), an energy-ray curable acrylic oligomer or acrylic polymer resin, a photoinitiator consisting of benzophenone, acetophenone, dibenzyl, diacetyl, diphenyl sulfide and/or azobisisobutyronitrile, and a crosslinking agent consisting of melamine, urea-formaldehyde, isocyanate functional prepolymer, a phenolic curing agent, and/or an amino-group curing agent; and (b) forming the phenoxy resin composition into a film or sheet having a thickness of 25-1000 microns by a solvent casting or melt extrusion method.    n = 35-400.