Improving the hydration resistance of CaO aggregates is the key to successful application of lime-based refractories in metallurgical industry. Additive Zr(OH)(4) and Al(OH)(3) were introduced in the preparation of CaO granules using granulation equipment and calcination method in this study. The results showed that the hydration resistance of CaO granules was improved significantly, especially for granules with 0.6 wt.% Zr(OH)(4) and 0.9 wt.% Al(OH)(3), respectively. The shell of CaO granules was relatively dense after calcination and the volume of open pores of CaO granules decreased from 3.56x10(-2) to 1.80x10(-2) cm(3)/g when additive was introduced. Zr(OH)(4) and Al(OH)(3) have the opposite effect on the closed porosity of CaO granules, the closed porosity of CaO granules was decreased with Zr(OH)(4) addition, but increased with Al(OH)(3) addition.