In　this　work,　a　recyclable　self-floating　A-GUN-coated　(Ag/AgCl@g-C3N4@UIO-66(NH2)-coated)　foam　was　fabricated　for　effective　inactivation　of　Microcystis　aeruginosa　(M.　aeruginosa)　under　visible　light.　The　floating　photocatalyst　was　able　to　inactivate　98%　of　M.　aeruginosa　within　180　min　under　the　visible-light　irrigation,　and　the　floating　photocatalyst　exhibited　a　stable　performance　in　various　conditions.　Moreover,　the　inactivation　efficiency　can　still　maintain　nearly　92%　after　five　times　recycle　experiments,　showing　excellent　photocatalytic　stability.　Furthermore,　effects　of　A-GUN/SMF　floating　catalyst　on　the　physiological　properties,　cellular　organics,　and　algal　functional　groups　of　M.　aeruginosa　were　studied.　The　floating　photocatalyst　can　not　only　make　full　use　of　excellent　photocatalytic　activities　of　A-GUN　nanocomposite,　but　also　promote　contact　between　catalyst　and　algae,　and　realize　the　effective　recovery　of　the　photocatalyst.　Finally,　possible　photocatalytic　inactivation　mechanisms　of　algae　were　obtained,　which　provides　references　for　removing　cyanobacteria　blooms　in　real　water　bodies.