Climate pollution and global warming caused by greenhouse gases have become one of our toughest environmental challenges. CO2 capture and separation from natural gas can effectively reduce CO2 emissions and improve energy efficiency, accordingly, it is a serious challenge faced by industrial separation and scientific research to effectively reduce the carbon dioxide concentration in natural gas pipeline transportation and achieve the acquisition of high-purity methane (>99.5 %). In this study, three stable hexanuclear microporous rare earth cluster-based MOFs (Sm-BDC-NH2, Er-BDC-NH2, Y-BDC-NH2) were successfully synthesized. The selectivity of CO2/CH4 was improved by the introduction of amino groups to achieve better CO2/CH4 separation performance, which was proved by dynamic penetration experiments.