In　this　study,　a　facile　strategy　for　in　situ　growth　of　covalent　triazine　frameworks　(CTFs)　membrane　on　alpha-Al2O3　substrate　was　presented.　An　intact　CTFs　based　composite　membrane　was　obtained　in　a　solvothermal　growth　process.　The　structure　and　property　of　the　CTFs　composite　membranes　were　investigated.　The　results　indicated　that　CTFs　could　grow　in　the　pores　of　the　alpha-Al2O3　substrate　to　modify　the　transport　channel.　Due　to　the　sieving　effect　of　the　CTFs　aperture,　the　prepared　CTFs　composite　membrane　exhibited　superior　rejection　for　different　types　of　dyes　(＞97%)　with　extremely　low　rejection　for　salts　(＜20%).　Moreover,　the　CTFs　composite　membrane　had　a　high　permeability　(448　L　m(-2)h(-1)　MPa-1)　and　good　stability　for　dye　desalination.　This　approach　demonstrated　the　great　potential　of　CTFs　membranes　for　dye/salt　separation.