Abstract: Sub-micron Al₂O₃ was added into CeO₂-ZrO₂ to form precursors powder which was hot press-sintered in vacuum atmosphere to form composite ceramics.The crystalline phase and structure of sintered ceramics were characterized with X-ray diffraction and scanning electron microscopy.The density and mechanical properties were also tested.The experimental results indicated that the Al₂O₃ enhanced the density,strengthened the material grains boundary,and part of Al₂O₃ has merged to the matrix particle,formed the transgranular structure.Compared to non-doped ZrO₂,the hardness,bending strength and the fracture toughness of the Al₂O₃ doped ceramics were improved.