Floating　photocatalysis　material　has　a　big　advantage　over　powdery　suspending　one　for　deep　purification　of　pollutants　in　colored　wastewater,　in　consideration　of　its　excellent　flexibility,　high　light-harvesting,　and　convenient　recycling　in　suspension　solution　systems.　As　a　result,　the　design　and　synthesis　of　floating　photocatalyst　are　of　great　importance.　Herein,　we　concentrate　on　the　preparation　of　metal-free　triazine-based　porous　organic　polymer　(POP)　as　a　visible-light　photocatalyst　on　biomass　waste　poplar　catkins　(PCs)　to　construct　a　reusable　floating　photocatalysis　system　via　a　soft　synthesis,　that　is,　trigonal-symmetrical　melamine　(M)　is　coupled　with　triformylphloroglucinol　(TFP)　monomer　to　obtain　photoactive　conjugated　POPM-TFP　loaded　on　soft　and　light　PC　microfibers　(Named　as　PC/POPM-TFP).　When　PC/POPM-TFP　(20　mg)　is　floated　on　the　polluted　water,　it　can　convert　100%　Cr(VI)　(50　mL,　10　mg/L)　in　80　min　into　Cr(III)　species　which　are　then　partly　synchronously　immobilized　(56.9%)　to　lessen　the　rerelease　of　Cr　element,　or　degrade　100%　methylene　blue　(MB,　60　mL,　10　mg/L)　after　100　min　of　visible-light　irradiation.　Moreover,　the　film-like　flexible　self-supporting　PC/POPM-TFP　also　exhibits　well　catalytic　activities　and　excellent　reusability　for　multipurpose　water　purification　under　real　natural　conditions.　The　molecular　oxygen　in　the　solution　gains　electrons　from　PC/POPM-TFP　to　generate　•O2–,　which　is　involved　in　photoreduction　of　Cr(VI)　besides　photo-induced　electrons,　and　mainly　contributes　to　photooxidation　degradation　of　MB.　The　proposal　of　floating　PC/POPM-TFP　not　only　avoids　the　risks　to　release　metal　ions　into　water　during　utilization,　which　will　cause　secondary　pollution,　but　also　provides　an　alternative　method　to　overcome　the　limitations　of　powdery　photocatalyst　for　recycling.　Overall,　this　study　assists　the　assembly　of　green　floating　photocatalysis　systems　to　allow　a　versatile　solid　surface　activation　for　establishing　more　energy　efficient　and　robust　catalysis　process　under　visible　light.　©　2022　Elsevier　B.V.