The invention relates to a method for preparing an MOFs material capable of adsorbing CO2 in biogas under room temperature conditions. The method comprises the following steps: sequentially adding cobaltous acetate tetrahydrate, citric acid monohydrate and alkaline substances into a mixed solvent of an organic solvent and water with a volume ratio of 1:1 to prepare a mixed solution by adopting a hydrothermal method, transferring the mixed solution into a hydrothermal kettle, placing the hydrothermal kettle in a drying oven, heating to the temperature of 120 DEG C, and preserving the temperature; and cooling to room temperature, filtering, washing through ethyl ether, naturally drying at room temperature, and obtaining purple prismatic crystals. The prepared cobalt citrate crystal material has the pore diameter of 4.5 angstroms, the area of a diamond-shaped window is 3.3*5.4 square angstroms, and the material can be effectively applied to adsorbing CO2 in the biogas under room temperature conditions.