The invention relates to a stepwise preparation method of a high-stability rare-earth organic framework material. The stepwise preparation method comprises the following steps: (1) preparing a hexanuclear rare-earth oxygen-cluster complex with a structure-directing agent; and (2) reacting the prepared hexanuclear rare-earth oxygen-cluster complex with organic ligand, thereby obtaining the high-stability rare-earth organic framework material. The technical scheme adopted comprises the following steps: dissolving rare-earth salts and the structure-directing agent in a mixed solution of dimethyl formamide and water; after uniform ultrasonic treatment, transferring into a sealed container, heating and maintaining for one day; after cooling, maintaining at room temperature for two weeks to obtain the hexanuclear rare-earth oxygen-cluster complex; cleaning, filtering and drying; dispersing the hexanuclear rare-earth oxygen-cluster complex and the organic ligand in a mixed solution of an organic solvent, water and nitric acid, after uniform ultrasonic treatment, transferring into the sealed container, heating and maintaining for two days; and naturally cooling to room temperature, thereby obtaining the high-stability rare-earth organic framework material. The high-stability rare-earth organic framework material can be used for gas adsorptive separation, detection and sensing, pollutant removal and the like in severe environments and strong-acid and strong-alkali environments.