Abstract: Optical transparent polycrystalline Al₂O₃ ceramics were fabricated by conventional solid-state pressureless sintering processing using high-purity powder of Al₂O₃（＞99.9wt%purity）. The effects of Y₂O₃ additive, sintering temperature and sintering holding time on the microstructure and optical properties of Al₂O₃ were investigated. The results indicate that small amounts of Y₂O₃ additiveinhibit the grain growth of the specimens, but the porosity increases with the increase of Y₂O₃ content.The optimum optical properties are obtained for the specimens sintered at 1800℃. The grain size increases and the porosity decreases with prolonging the sintering holding time.