To replace lead oxide glass, Bi2O3-SiO2-ZnO glass, as a Pb-free glass, was examined for optical properties for a transparent dielectric layer of a plasma display panel (PDP). The glass was evaluated for glass transition temperature (Tg) and thermal expansion coefficient (α). The transparent thick films produced with a screen-printing method were evaluated for optical properties. The transmittance of thick films fired at 560-620°C showed above 80%. The results suggest that the bismuth glass is a suitable candidate for one of the lead-free glasses compositions in a transparent dielectric layer.