Compared　to　traditional　treatment　methods,　the　catalytic　ozonation　process　based　on　an　advanced　and　reliable　ozone　generator　and　highly　efficient　catalysts　has　shed　new　light　on　treating　algal　blooms　in　water　bodies.　In　this　study,　Ag3PO4/NiAl-LDH　nanocomposites　were　synthesized　by　a　two-step　co-precipitation　method,　characterized,　and　applied　as　ozonation　catalysts　for　the　inactivation　of　Microcystis　aeruginosa.　Under　controlled　conditions,　the　nanocomposite　(ANA-10)　with　an　Ag3PO4:　NiAl-LDH　weight　ratio　of　1:10　exhibited　excellent　catalytic　ozonation　performance　and　reusability,　effectively　achieving　a　nearly　complete　algae　removal　within　60　min.　The　rate　constant　of　ANA-10　reached　approximately　0.0958　min-1,　being　6.4-,　2.8-,　and　2.1-fold　higher　than　that　of　individual　O3,　Ag3PO4,　and　NiAl-LDH,　respectively.　The　variations　in　the　physiological　properties　of　the　algal　cells　reflect　severe　damage　and　destruction　of　their　cellular　morphology,　membrane　permeability,　intracellular　and　extracellular　organics,　proteins,　and　antioxidant　system　during　the　ANA-10　catalyzed　ozonation　process.　Electron　spin　resonance　(ESR)　and　quenching　experiments　indicated　that　algae　inactivation　can　be　attributed　to　the　formed　reactive　oxygen　species　(ROS),　such　as　center　dot　OH,　center　dot　O2-　and　1O2.　In　addition,　the　mechanism　of　ROS　formation　over　ANA-10　was　clarified　and　involved　Ag3PO4-assisted　enhancement　of　the　redox　of　Ni2+/Ni3+　and　accelerated　surface　hydroxylation.　Overall,　this　study　offers　useful　insights　into　the　control　of　harmful　cyanobacterial　blooms.