The Al2O3-ZrB2 nanocomposite ceramics were prepared and the mechanical properties of the process parameters’ effect were studied. The results showed that: Among the various values of sintering temperatures applied, a maximum Vickers hardness of 1897HV and high reliability were attained at 1500 癈 and at atmosphere sintering. In addition, the sample was not well densified under the sintering temperature. Scanning electron microscopy (SEM) showed that fine ZrB2 particles dispersed and pinning at grain boundaries to inhibit grain boundary movement effectively. While larger ZrB2 particles distributed between A12O3 particles uniformly and occupy A12O3 particles grow space to hinder the matrix grains, which greatly promoted the densification of the ceramic, improving the microstructure. Fracture morphology indicates that trans-granular fracture was occurred, the ceramic material having high toughness.