Thermal stability and wear resistance of nanoceramic materials are excellent, so it is an ideal die material and has become one of the increasingly important topics in the field of die research. A new 3Y-TZP nanocomposite die material was prepared with hot pressing technique by using 3Y-TZP, CeO2, Al2O3 and nanometer sized TiC as raw materials. Effects of CeO2 on the mechanical property and microstructure of 3Y-TZP nanocomposite die material were investigated. The addition of CeO2 has obvious effect on the flexural strength and fracture toughness. When the content of CeO2 is 2mol%, the fracture toughness of the composite material reaches 11.22MPa•m1/2. With the increase of CeO2 content, the fracture toughness becomes lower, the flexural strength and hardness first increase and then decrease. When the CeO2 content is 6mol%, the maximum flexural strength reaches 866MPa. The reason for the improvement of mechanical property can be attributed to the effect of CeO2 on the phase transformation of t-ZrO2 and microstructure and the resulted phase transformation toughening mechanism.