A purification method for preparing high-purity alumina through vacuum reduction distillation is disclosed. The method can be used for purifying industrial type fine Al2O3 powder having common purity. The method is characterized in that the method includes (1) fully mixing the Al2O3 having common purity with high-purity carbon reductant fine powder according to a certain ratio; (2) then adding the mixture into a vacuum distillation furnace, vacuumizing the furnace to a certain vacuum degree, then electrifying the furnace, heating the mixture to a certain temperature, maintaining the temperature, and performing reduction distillation to allow impurities including Na2O, SiO2, Fe2O3, TiO2, ZnO2, MgO and CaO in the Al2O3 to be reduced into metal through C in the carbon reductant fine powder, to allow Na, Mg and Ca (and crystal H2O and CO2) to be volatized, to allow Al2O3 to be not reduced or melt or volatized, and to allow molten Fe to be deposited below the Al2O3 because of gravity; and (3) collecting residues after the reduction and the evaporation, removing molten Fe or solid-state Fe under the residues to obtain the high-purity AlO3 fine powder, and condensing and collecting condensed molten metal Na, Zn, Mg and Ca of evaporated gas separately or in a mixed manner.