The invention discloses a method for separating methane and nitrogen gas. The method comprises the following steps: taking a metallic organic frame material as an adsorbing agent, and separating the methane and the nitrogen gas or purifying the methane from mixed gas, which contains the methane and the nitrogen gas, by adopting an adsorption and separation method; the structural general formula ofthe metallic organic frame material is [M(C6O4)].nH2O or [M2(C6O4)3].nH2O, in the formula, M is a metal ion, n is the number of water molecules, and the numerical value is 2-8. The metallic organic frame material has a three-dimensional network structure formed through coordination bonds or intermolecular force of transitional metal ions or alkaline-earth metal ions and organic ligands (2,5-dyhydroxyl-1,4-benzoquinone), wherein the water molecules coordinate with metal and have relatively strong hydrogen-bond interaction with oxygen atoms on the organic ligands. The organic ligands and metalsalt used for preparing the metal organic frame material utilized by the method provided by the invention are both cheap and easy to obtain, the synthetic conditions are mild, the purification steps are simple, and the operation and amplification are facilitated.