Removal of carbon dioxide (CO2) from a CO2/N2 mixture by utilizing CO2-selective sorbents is important from the perspective of energy security and environmental sustainability. Herein, a microporous metal-organic framework (MOF) composed of manganese(II) and a bifunctional linker 5-(4H-1,2,4-triazol-4-yl)benzene-1,3-dicarboxylic acid (H2L), [Mn(HL)2] (1) is designed and synthesized using a hydrothermal method. Characterized by single-crystal X-ray diffraction (SCXRD), a microporous channel was found in the structure of compound 1 along the a-axis. Attributed to hydrogen-binding interactions between CO2 molecules and N- and O-donor ligands in its microporous one-dimensional (1D) channel, compound 1 exhibits favorable adsorption of CO2 over N2. Further, verified by experimental breakthrough tests, the CO2/N2 mixture can be separated efficiently. This work provides potential guidance for designing CO2-selective MOFs for CO2/N2 separation.