Y2O3-MgO nanocomposite powders have been prepared by ball mill using the commercial Y2O3, MgO powders. The crystal structure, morphology, uniformity of the Y2O3-MgO nanocomposite powder have been characterized by XRD, SEM, EDS respectively. And then the hot-pressing has been used to densify of the Y2O3-MgO nanocomposite ceramic. The FTIR and Vickers hardness tester have been used to reveal the optical and mechanical properties of Y2O3-MgO nanocomposite ceramic with different preparation parameter. The transmittance and hardness reach to 80% (6μm) and 12.3 GPa respectively with optimal conditions.