Organic　solvent　nanofiltration　(OSN)　is　one　of　the　fast　development　areas　of　membrane　separation.　The　nano　filtration　performances　of　membranes　are　mainly　depended　on　the　thickness　of　separation　layers　and　the　orientation　of　separation　channels.　Herein,　an　ultrathin　alpha-Co(OH)(2)　film　was　fabricated　through　the　in　situ　growth　of　alpha-Co(OH)(2)　nanosheets　on　alumina　tubular　substrate　for　OSN.　The　thickness　of　the　film　was　approximately　300　nm　and　the　alpha-Co(OH)(2)　nanosheets　were　vertically　grown　to　leave　channels　perpendicular　to　the　substrate.　The　orientation　growth　and　interlayer　gallery　of　the　alpha-Co(OH)(2)　layer　were　confirmed　by　SEM,　PXRD　and　SAXS　characterization.　The　resulting　composite　membrane　exhibits　high　fluxes　for　organic　solvents.　Particularly,　in　separating　eriochrome　black　T　from　methanol　solution,　the　permeance　could　reach　127　L　m(-2)　h(-1)　bar(-1).　We　anticipate　that　the　facile　fabrication　method　and　excellent　separation　performances　make　the　alpha-Co(OH)(2)　composite　membrane　have　a　great　application　potential　in　OSN.