A　novel　floating　photocatalyst　was　prepared　by　depositing　Ag/AgCl@ZIF-8　on　a　sodium　dodecyl　benzene　sulfonate　modified　sponge　with　a　simple　dip-coating　method　and　was　employed　for　the　inactivation　of　harmful　cyanobacteria　for　the　first　time.　The　effect　of　coated　sponge　on　Microcystis　aeruginosa　under　visible　light　was　investigated　and　a　possible　mechanism　was　proposed.　The　results　showed　that　the　synthesized　photocatalyst　exhibited　outstanding　performance　with　a　high　removal　efficiency　of　chlorophyll　a　reaching　98.5%　after　4　h　and　revealed　excellent　stability　under　visible　light.　The　superoxide　radicals,　holes　and　hydroxyl　radicals　played　a　crucial　role,　which　causing　the　damage　of　cell　wall　and　membrane,　the　bleaching　of　pigments,　the　collapse　of　superoxide　dismutase　and　hydrogen　peroxidase　and　other　oxidation　stress　effects.　Above　all,　Ag/AgCl@ZIF-8　sponge　fabricated　from　this　simple　and　cost-effective　dip-coating　method　has　a　promising　prospect　for　the　removal　of　harmful　cyanobacteria　in　eutrophic　water　bodies.