In this paper, a TiB2 composite with nano-scale Al2O3 as dispersion phase was hot-pressed at 1750. The effect of nano-scale Al2O3 on sinterability and mechanical properties of the TiB2 was investigated. The results show that the relative density of sintered body increases firstly and then decreases with the increasing of the Al2O3 content. When containing 10vol% nano-scale Al2O3, the composite with fine and uniform grains is obtained and the flexural strength reaches maximum. The nano-scale Al2O3 may agglomerate together when the Al2O3 content is up to 20vol%, which is harmful to the densification and mechanical properties of the composite.