The　discharge　of　oily　wastewater　poses　a　serious　threat　to　human　health　and　the　ecological　environment.　The　development　of　effective　oil-water　separation　techniques　is　critical　to　addressing　this　issue.　Herein,　a　side-chain　engineering　strategy　was　proposed　to　construct　nanoscale　covalent　organic　frameworks　(COFs)　decorated　stainless　steel　nets　(SSN)　with　tunable　wettability　(SSN@COFs-C)　via　the　introduction　of　three　distinct　lengths　of　alkyl　chains.　The　nanoscale　COFs　particles　were　uniformly　distributed　on　the　SSN　substrate,　resulting　in　a　hierarchical　surface　structure　that　significantly　enhanced　the　material’s　hydrophobicity.　Unlike　conventional　approaches,　COFs　provide　a　robust　and　tunable　platform　to　address　challenges　in　achieving　durable　superhydrophobic　surfaces　and　overcome　key　development　barriers　such　as　stability　and　reusability.　The　SSN@COFs-C　exhibited　high　hydrophobicity　(water　contact　angle　of　151.1-157.3°)　and　self-cleaning　properties.　The　optimal　composite　was　capable　of　separating　immiscible　oil/water　mixtures　with　a　flux　of　6079　L　m-2　h-1　and　exhibited　an　oil/water　separation　efficiency　exceeding　99.0%.　Moreover,　it　effectively　separated　surfactant-stabilized　water-in-oil　emulsions　with　a　separation　efficiency　greater　than　99%　and　retained　their　performance　after　multiple　reused　cycles.　This　work　provides　insight　into　the　fabrication　and　application　of　nanoscale　hydrophobic　oil-water　separation　composites.　©　2025　American　Chemical　Society.