Sulfur　hexafluoride　(SF6)　holds　substantial　value　for　purification　and　recycling　in　environmental　governance　and　resource　optimization　because　of　its　significant　greenhouse　effect.　In　this　paper,　a　series　of　halogenated　COF-637　structures　were　obtained　by　designing　and　regulating　the　types,　numbers,　and　modification　sites　of　halogen　atoms.　The　optimal　halogenated　structure　for　selective　adsorption　of　SF6/N2　was　determined　by　Grand　Canonical　Monte　Carlo　(GCMC)　simulations　and　Density　Functional　Theory　(DFT)　calculations.　Results　indicate　that　under　conditions　of　298　K　and　1　bar,　COF-p-X　(X　=　F,　Cl,　Br,　where　＇p＇　represents　halogen　substitution　at　the　para-position　on　the　phenyl　ring　of　the　tetraphenylphenyl　side　chain)　exhibits　good　selective　separation　performance　for　SF6/N2　mixtures.　Among　them,　COF-p-Br　shows　the　highest　selectivity　of　331.29,　with　an　SF6　adsorption　capacity　of　1.77　mmol/g.　In　contrast,　COF-p-F　exhibits　a　higher　SF6　uptake　of　6.35　mmol/g,　along　with　a　selectivity　of　290.4,　outperforming　most　previously　reported　adsorbents.　Theoretical　analysis　reveals　that　the　halogen-functionalized　pores　can　engage　in　multiple　C-X···F(SF6)　interactions.　Notably,　the　COF-p-Br　with　smaller　pore　characteristics　exhibits　the　highest　adsorption　energy　and　Bader　charge　transfer　in　the　SF6@COF-p-Br　system.　To　elucidate　how　halogen　atoms　modulate　the　electronic　structure　of　the　framework,　total　density　of　states　(TDOS),　electrostatic　potential　maps,　and　local　charge　distribution　analyses　have　been　conducted.　This　research　not　only　provides　insights　into　the　adsorption　mechanisms　of　halogenated　COFs　but　also　offers　theoretical　support　for　designing　high-performance　SF6　purification　materials.　©　2025