Macro-porous alumina ceramics were prepared by the gel-casting method using sacrificial polystyrene spheres as the template. The resulted porous alumina ceramics have regularly arranged pores and high cell wall densities, which confer high mechanical strength to the porous ceramics. The highest compressive strength for a porous alumina ceramic, with a relative density of 30%, in this work is 28MPa, which is at least 74% higher than that of previously reported porous alumina ceramics with the same porosity. The results show that the cell wall density, window size and cell size can be adjusted by controlling the sintering temperature, solid loading percentage of the alumina slurry and the size of the polystyrene spheres. With the increase in cell wall density and decrease in cell size and window size, the compressive strength of the porous alumina increases. Thus, a novel porous structure with high porosity and high strength can be made by this flexible method which is also suitable for making complicated shapes and large sizes.