Uncontrolled　ion　transport　and　susceptible　SEI　films　are　the　key　factors　that　induce　lithium　dendrite　growth,　which　hinders　the　development　of　lithium　metal　batteries　(LMBs).　Herein,　a　TpPa-2SO(3)H　covalent　organic　framework　(COF)　nanosheet　adhered　cellulose　nanofibers　(CNF)　on　the　polypropylene　separator　(COF@PP)　is　successfully　designed　as　a　battery　separator　to　respond　to　the　aforementioned　issues.　The　COF@PP　displays　dual-functional　characteristics　with　the　aligned　nanochannels　and　abundant　functional　groups　of　COFs,　which　can　simultaneously　modulate　ion　transport　and　SEI　film　components　to　build　robust　lithium　metal　anodes.　The　Li//COF@PP//Li　symmetric　cell　exhibits　stable　cycling　over　800　h　with　low　ion　diffusion　activation　energy　and　fast　lithium　ion　transport　kinetics,　which　effectively　suppresses　the　dendrite　growth　and　improves　the　stability　of　Li+　plating/stripping.　Moreover,　The　LiFePO4//Li　cells　with　COF@PP　separator　deliver　a　high　discharge　capacity　of　109.6　mAh　g(-1)　even　at　a　high　current　density　of　3　C.　And　it　exhibits　excellent　cycle　stability　and　high　capacity　retention　due　to　the　robust　LiF-rich　SEI　film　induced　by　COFs.　This　COFs-based　dual-functional　separator　promotes　the　practical　application　of　lithium　metal　batteries.