Hierarchical porous alumina ceramics were prepared through hydratable alumina gel-casting method. The matrices were constructed by interlocked alumina platelets. Hollow glass spheres as pore formers participated in the fluorine-catalyzed structure formation process. The samples with 20 wt% hollow spheres added (1000–1300 °C) had volume densities, apparent porosities, linear shrinkages and compression strengths of 0.59–0.90 g/cm3, 81.68 %∼74.20 %, 1.40 %∼14.07 % and 12.64–23.36 MPa, respectively. Changing the fraction of hollow spheres (10–30 wt%, 1100 °C) had effects on tailoring the compression strengths (3.13–13.40 MPa), without apparently affecting the densities (0.58–0.60 g/cm3)/porosities (79.70 %∼82.28 %)/shrinkages (1.47 %∼1.93 %). The pore size distributions demonstrated the interlocking pores built by alumina platelets, the pores that inherited from the gel network, and the large pores provided by hollow spheres. The reheated (1300 °C) samples presented good structure stability with shrinkages of 6.60 %∼18.57 %. The synthesized ceramics with both high porosities and satisfactory strengths could meet the requirements of high temperature gas/liquid filtration or catalyst supporting, etc.