Temperature　is　the　key　important　factor　affecting　sludge　bulking.　To　investigate　the　mechanism　of　sludge　bulking　at　different　temperature　shockings,　themicrobial　community　structure　and　dominant　filamentous　bacteria　in　sequencing　batch　reactor　(SBR)　treating　domestic　sewage　under　abruptly/gradually　temperature　decreasing　conditions　were　analyzed　by　Illumina　MiSeq　high-throughput　sequencing　technology.　The　results　showed　that　Microthrix　Parvicella　was　the　dominant　filamentous　bacteria　in　the　abruptly　temperature　dropping　system　in　which　the　sludge　volume　index　(SVI)　increased　up　to　291mL/g,　while　filamentous　bacteria　Eikelboom　Type　0092　was　the　dominant　in　the　gradually　decreasing　system　in　which　the　SVI　was　maintained　at　250mL/g.　Therefore,　temperature　shocking　can　provide　more　suitable　habitat　for　Eikelboom　Type　0092.　The　temperature　varying　process　will　also　lead　to　significant　differences　in　the　community　structure.　The　relative　abundance　of　Proteobacteria　maintained　at　average　of　39.3%,　and　showed　little　variation,　but　the　Actinobacteria　and　Chloroflexi　showed　totally　different　trends.　The　mean　relative　abundance　of　microorganisms　related　to　organic　matter　removal　was　stable　at　13.6%,　and　for　Nitrospira　it　was　about　2.48%　accounting　for　more　than　80%　of　the　total　NOB.　Limited　filamentous　bulking　(LFB)　of　Eikelboom　Type　0092　caused　by　gradually　temperature　decreasing　could　not　lead　to　serious　deterioration　of　effluent　quality,　and　removal　rate　of　COD　and　NH4+-N　were　better　than　temperature　abruptly　dropping　system.　©　2022,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.