The invention relates to a macropore-mesopore ordered magnesium-aluminum composite oxide material and a preparation method thereof. The preparation method comprises the following steps of dissolving inorganic acid, organic carboxylic acid, a block copolymer non-ionic surfactant, a magnesium source and an aluminum source into absolute ethyl alcohol, preheating in solvent under the sealing condition at high pressure, adding organic high polymer microspheres, volatilizing the solvent under the opening condition, and calcining at the temperature of 450 to 750 DEG C, so as to obtain the macropore-mesopore ordered magnesium-aluminum composite oxide material. The prepared macropore-mesopore ordered magnesium-aluminum composite oxide material has the advantages that the lattice three-dimensional ordered macroporous structure, the highly regular ordered two-dimensional hexagonal mesoporous structure and the larger specific surface area and pore volume are realized; the diameters of macropore and mesopore can be adjusted; the alkaline matter can be highly and uniformly dispersed in the wall of mesopore at atom level; the heat stability is higher, and the alkaline catalytic conversion property on organic macromolecules is effectively improved.