A wet jet milling process was used as a novel method to prepare Al2O3 slurries. The wet jet-milled slurries showed very low viscosity compared with the ball-milled slurries. Moreover, the viscosity of the wet jet-milled slurries was constant for long times, whereas that of the ball-milled slurries increased rapidly with time. Al2O3 particles after wet jet milling retained initial surface conditions, although Al2O3 particles after ball milling yielded more OH groups on the surface. Casting rate was sensitive to the solid content and preparation method of slurry. The relative density of the green bodies prepared from the wet jet-milled slurries was about 65% or more and was independent of the slurry solid content. On the other hand, the relative density of the green bodies prepared from the ball-milled slurries increased with increasing solid content and was higher than 60% at the solid content of 50% by volume. Linear shrinkage of the sintered bodies prepared from the wet jet-milled slurries was very low and independent of the solid content of the slurry whereas that of the sintered bodies prepared from the ball-milled slurries increased with decreasing solid content.