NOVELTY - Metal-organic framework material comprises a metal salt, an organic ligand coordination compound and a solvent which is provided with a multi-cavity structure. The organic ligand is nitrogen, oxygen or sulfur atoms. The metal salt is aluminum(III), iron(III), iron(II), lithium(I), magnesium(II), cobalt(II), nickel(II), copper(II), zinc(II), manganese(II), zirconium(II), lanthanum(III) or samarium(III). The metal salt has stable room temperature and pressure, and is soluble in water. The solvent is e.g. ethanol or dimethylformamide, methyl formate, acetate or oxalate.    USE - The framework material is useful in the purification of methane gas containing nitrogen and carbon dioxide, and absorption and separation of methane (all claimed).    ADVANTAGE - The framework material has stable property, and porous structure which is suitable for separation and purification of low quality and high-concentration methane gas. The method has simple preparation procedures, high production yield, and relatively mild reaction conditions; and utilizes easily available raw materials.    DETAILED DESCRIPTION - Metal-organic framework material comprises a metal salt, an organic ligand coordination compound and a solvent which is provided with a multi-cavity structure. The organic ligand is nitrogen, oxygen or sulfur atoms. The metal salt is aluminum(III), iron(III), iron(II), lithium(I), magnesium(II), cobalt(II), nickel(II), copper(II), zinc(II), manganese(II), zirconium(II), lanthanum(III) or samarium(III). The metal salt has stable room temperature and pressure, and is soluble in water. The solvent is ethanol or dimethylformamide, methyl formate, acetate, oxalate, carbonate, basic carbonates, nitrates, sulfate, hydroxide or chloride. The organic ligand is monodentate, bidentate or tridentate organic compound. The framework material is a porous material, having Langmuir nitrogen specific surface area is 20 m2/g, and the pore size distribution is 0.4-2 nm. INDEPENDENT CLAIMS are also included for:    (1) preparing the framework material, comprising (i) dissolving metal salt and organic ligand in corresponding solvent, simultaneously adding deprotonated base, and uniformly stirring at room temperature to obtain a mixture, (ii) maintaining the temperature of the mixture at 0-180 degrees C, reacting by adding the solvent for 0.5-72 hours, and saturating under steam pressure to obtain a precipitate, then cooling, filtering the precipitate, washing, and drying the precipitate for 4-24 hours at 60-120 degrees C under drying conditions, and (iii) drying the obtained product, uniformly mixing by adding 2-4% graphite and 0-10% polyvinylpyrrolidone, molding, and activating at 80-200 degrees C for 2-24 hours, to form an adsorbent; and    (2) use of framework material in the purification of methane gas containing nitrogen and carbon-dioxide, where the equilibrium separation factor of methane-nitrogen is greater than 3, and equilibrium separation factor of carbon dioxide-methane is greater than 4.