The invention discloses a preparation method of an aluminum oxide porous material. The preparation method comprises the following steps of modifying an aluminum oxide powder by a magnesium phosphate sol, adding a manganese oxide micropowder as a sintering additive, and reducing the firing temperature of the aluminum oxide porous material to the temperature of 1200 to 1400 DEG C. The preparation method has the advantage that the good pore structure can be obtained for the porous material within the wide firing temperature range. The aluminum oxide porous material prepared by the preparation method has excellent mechanical property.