Spherical porous alumina particles were prepared by mixed solvent to control the reaction rate of Al-alkoxide and the particle shape with hydroxy-propyl cellulose(HPC). HPC was used as a dispersant to prevent aggregation during the formation of particles. The effect of [H2O]/[ASB] ratio on the crystallization reactions of as-prepared particles was studied by XRD, FT-IR, and TG-DTA analysis. The mole ratio of water and Al-alkoxide added in the condensation reaction had an important effect on the crystal structure of as-prepared particles and the calcined particles. As the [H2O]/[ASB] ratio increase, the crystal structure of as-prepared particles was continuously varied from amorphous Al(OH)3 to pseudo-boehmite with chemical composition of AlO(OH). The samples which have higher crystallinite after drying process were transformed into the δ-and θ-Al2O3 at lower calcination temperature, but these sample were transformed into α-Al2O3 at higher calcination temperature. This result was thought to be the transformation of the coordination number of Al(3+) ion in the crystal structure. The particles prepared by [H2O]/[ASB]=2 condition crystallized to α-Al2O3 at 600℃ and converted to η-Al2O3 at 1,100℃ without intermediate phases.