The　detection　of　trace　water　(H2O)　content　is　important　and　challenging　in　food　and　food-related　industries.　Herein,　highly　crystalline　two-dimensional　covalent　organic　frameworks　(TAPT-BTCA-COF)　with　yellow-green　fluorescence　were　prepared　by　using　1,3,5-tris(4-aminophenyl)triazine　(TAPT)　and　1,3,5-benzenetricarboxaldehyde　(BTCA)　as　precursors.　The　fluorescence　of　TAPT-BTCA-COF　is　sensitive　to　the　solvent　polarity　due　to　the　intermolecular　charge　transfer　(ICT)　effect　and　can　be　quenched　by　trace　H2O　due　to　the　block　of　ICT　effect　by　H2O.　On　this　base,　TAPT-BTCA-COF　is　applied　for　sensing　of　trace　H2O　in　common　organic　solvents　such　as　DMF,　acetonitrile,　THF　and　acetone　with　fast　response　and　high　sensitivity.　The　limits　of　detection　for　H2O　in　DMF,　acetonitrile,　THF　and　acetone　are　0.082　wt%,　0.0053　wt%,　0.0091　wt%　and　0.0061　wt%,　respectively.　Furthermore,　a　ratiometric　fluorescent　sensor　is　proposed　by　using　TAPT-BTCA-COF　as　the　signal　probe　and　red　fluorescent　tris(2,2′-bipyridyl)ruthenium(II)　dichloride　as　the　reference　and　successfully　applied　for　quantitatively　and　semi-quantitatively　sensing　of　trace　H2O　in　honey　sample　and　the　moisture　in　N2　gas.　©　2021　Elsevier　B.V.