The　poor　light　transmittance,　low　recycling　rate　and　potential　secondary　pollution　problems　of　powder　photo　-catalysts　limit　the　practical　application　of　photocatalytic　technology.　Therefore,　there　is　an　urgent　need　to　develop　stable　floating　photocatalysts　to　alleviate　the　problem　of　harmful　algal　blooms　(HABs).　In　this　work,　a　floating　Ag2MoO4/TACN@LF　composite　was　synthesized　for　the　inactivation　of　Microcystis　aeruginosa　(M.　aeruginosa)　by　employing　a　simple　oscillatory　impregnation　method.　The　Ag2MoO4/TACN@LF　floating　photocatalyst　exhibited　stable　algae　removal　performance　under　various　conditions,　and　100%　chlorophyll　a　removal　rate　could　be　achieved　within　4　h　of　visible　light　irradiation　under　the　optimal　photocatalyst　loading　of　6　g/L.　The　effects　of　Ag2MoO4/TACN@LF　floating　catalyst　on　algal　cell　membrane　permeability,　phycobiliprotein,　intracellular　antioxidant　enzyme　activities　and　algal　organic　matter　were　further　studied.　Moreover,　the　scavenging　experiments　demonstrated　that　center　dot　OH　was　the　predominant　reactive　oxygen　species　(ROSs).　Ag0　and　3g-C3N4　*　also　made　a　non-negligible　contribution　to　the　inactivation　of　algal　cells.　What＇s　more,　the　Ag2MoO4/　TACN@LF　still　exhibited　92%　inactivation　efficiency　for　M.　aeruginosa　after　5　cycles　reused　experiments,　indicating　its　promising　potential　for　practical　application　of　alleviating　HABs.