Photo-induced　reversible　complexation-mediated　polymerization　(RCMP)　is　a　green　and　economical　method　to　prepare　polymers　with　precise　molecular　weights,　narrow　molecular　weight　distributions　and　functionally　active　chain　ends.　Covalent　organic　frameworks　(COFs)　are　a　promising　heterogeneous　photocatalyst　for　mediating　RCMP　due　to　their　adjustable　structure,　band　gap,　and　porosity.　In　this　work,　1,3,5-triformylphloroglucinol　(Tp)　and　p-azoaniline　(Azo)　were　selected　to　construct　2D　beta-ketoenamine　linked　Tp-Azo-COF　as　a　heterogeneous　photocatalyst　to　trigger　RCMP　under　white　light　irradiation.　A　series　of　polymers　with　controllable　molecular　weight　and　narrow　molecular　weight　distribution　were　successfully　prepared　by　using　Tp-Azo-COF　as　photocatalysis.　On/off　light　experiments　confirmed　the　good　spatiotemporal　control　feature,　and　chain　expansion　experiments　demonstrated　the　high　＂activity＂　of　polymer　chain　ends.　Furthermore,　the　mechanistic　research　elucidated　that　electron　transfer　between　Tp-Azo-COF　and　initiator　occurred,　allowing　the　formation　of　reactive　radicals　to　mediate　RCMP.　Density　functional　theory　calculations　revealed　that　the　coordination　of　iodine　on　the　initiator　to　catalyst　obviously　reduced　the　bond　dissociation　energy,　leading　to　enhance　in　the　polymerization　rate.　This　work　provides　a　platform　for　constructing　heterogeneous　photocatalysts　with　more　efficient　and　stable　to　mediate　RCMP.