To　investigate　the　characteristics　of　microbial　diversity　during　filamentous　bulking　at　low　temperature,　the　induction　of　sludge　bulking　was　successfully　carried　out　using　a　low-temperature　sequencing　batch　reactor(SBR).　With　the　help　of　Illumina　MiSeq　high-throughput　sequencing　technology,　the　overall　changes　in　the　microbial　community　structure　of　activated　sludge,　the　characteristics　of　each　specific　microbial　community,　and　the　specific　genera　were　all　investigated　under　different　sludge　sedimentation　performances.　The　results　showed　that　filamentous　bulking　can　be　successfully　induced　after　the　system　operating　temperature　drops　to　(14±1),　and　the　COD　and　TN　removal　rates　can　still　be　maintained　at　approximately　90%　and　86%,　respectively,　with　the　sludge　volume　index　deteriorating　to　663.99　mL•g-1.　The　occurrence　of　sludge　bulking　at　low　temperature　will　not　only　reduce　the　overall　diversity　and　uniformity　of　microorganisms　in　the　system　and　increase　the　abundance　of　filamentous　bacteria　from　0.49%　to　26.04%　but　also　cause　the　abundance　of　denitrifying　bacteria　to　reduce　from　21.04%　to　13.99%　and　that　of　dephosphorization　bacteria　to　reduce　from　4.25%　to　1.93%.　Of　the　five　filamentous　genera　founded,　the　abundances　of　three　filamentous　bacteria　represented　by　Thiothrix　increased,　whereas　only　that　of　the　Haliscomenobacter　decreased.　Of　the　19　denitrifier　genera　founded,　the　abundances　of　five　species　represented　by　Nitrosomonas　increased,　whereas　those　of　seven　species　represented　by　Nitrospira　decreased.　Moreover,　the　abundances　of　Pseudomonas　and　Tetrasphaera　increased　out　of　the　eight　phosphorus-removing　bacteria　genera,　whereas　the　abundances　of　the　five　bacteria　genera　represented　by　Candidatus_Competibacter　decreased.　Although　sludge　bulking　has　a　significant　impact　on　the　structure　of　the　microbial　community,　the　477　operational　taxonomic　units　and　227　bacterial　species　that　are　always　present　in　the　different　sludge　samples　indicate　that　the　main　microorganisms　in　the　reactor　are　still　relatively　stable　during　the　bulking　process.　©　2020,　Science　Press.　All　right　reserved.