Adsorption　-based　C2H2　purification　is　a　promising　technology　in　the　petrochemical　industry,　but　the　seeking　or　design　of　suitable　adsorbents　faces　the　challenge　of　merging　excellent　separation　properties　with　other　implementable　advantages.　Here,　we　reported　a　cost-effective　and　easily　scalable　metal-organic　framework　(MOF),　BUT-316-a　(BUT　=　Beijing　University　of　Technology),　with　unprecedented　local-molecule-trap　(LMT)　for　the　preferential　adsorption　of　C2H2　over　CO2.　Attributed　to　the　existence　of　the　LMT,　high　density　of　open　metal　sites　(OMSs),　and　microporous　pore　structure,　BUT-316-a　combines　high　uptake　(117.6　cm3　cm　-3)　and　packing　density　of　C2H2　(0.36　g　mL-1),　coupled　with　good　C2H2/CO2　selectivity　(17.2).　The　practical　separation　performance　of　BUT-316-a　toward　C2H2/CO2　mixture　and　the　associated　host-guest　interactions　within　the　LMT　were　further　unveiled　by　dynamic　breakthrough　experiments　and　theoretical　calculations,　respectively.　This　study　may　provide　valuable　insights　into　designing　more　advanced　adsorbents　with　an　optimal　binding　environment　for　gas　separation.