In　this　work,　a　novel　Ag/AgCl@g-C3N4@UIO-66(NH2)　heterojunction　was　constructed　for　photocatalytic　inactivation　of　Microcystis　aeruginosa　(M.　aeruginosa)　under　visible　light.　The　photocatalyst　was　synthesized　by　a　facile　method　and　characterized　by　XRD,　SEM,　TEM,　BET,　XPS,　FT−IR,　UV–vis　DRS,　PL　and　EIS.　The　nanocomposite　can　not　only　provide　lots　of　active　sites,　but　also　improve　capacities　to　utilize　visible-light　energy　and　effectively　transfer　charge　carriers,　thus　enhancing　removal　efficiencies　of　cyanobacteria　(99.9%　chlorophyll　a　was　degraded　within　180　min).　Various　factors　in　photodegradation　of　chlorophyll　a　were　studied.　Besides,　changes　on　cellular　morphologies,　membrane　permeability,　physiological　activities　of　M.　aeruginosa　during　photocatalysis　were　investigated.　Moreover,　the　cycle　test　indicated　that　Ag/AgCl@g-C3N4@UIO-66(NH2)　exhibits　excellent　reusability　and　photocatalytic　stability.　Finally,　a　possible　mechanism　of　M.　aeruginosa　inactivation　was　proposed.　In　a　word,　Ag/AgCl@g-C3N4@UIO-66(NH2)　can　efficiently　inactivate　cyanobacteria　under　visible　light,　thus　providing　useful　references　for　further　removal　of　harmful　algae　in　real　water　bodies.　©　2020　Elsevier　B.V.