In　view　of　the　problems　of　slow　start,　easy　loss　and　sensitive　to　low　temperature　environment　in　the　suspension　culture　of　anaerobic　ammonia　oxidation　bacteria　(AnAOB)　suspension　culture,　polyvinyl　alcohol　(PVA)　was　used　to　prepare　the　anaerobic　ammonia　oxidation　(anammox)　immobilized　filler,　so　as　to　realize　the　rapid　start-up　and　activity　improvement　of　anammox.　Meanwhile,　the　response　of　nitrogen　removal　performance　of　encapsulated　biomass　to　temperature　reduction　was　determine　by　batch　experiment.　In　addition,　changes　in　the　internal　structure,　flora　composition　and　diversity　of　the　filler　were　analyzed　by　scanning　electron　microscopy　(SEM)　and　high-throughput　sequencing.　The　results　showed　that　the　nitrogen　removal　capacity　of　the　immobilized　filler　(E1)　was　significantly　higher　than　that　of　the　suspended　sludge　contrast　system　(S1)　after　100d　enrichment　culture.　The　final　nitrogen　removal　rate　reached　1.168kg·(m3·d-1)　-1,　and　the　total　nitrogen　removal　efficiency　was　92%.　The　immobilization　improved　the　resistance　of　AnAOB　to　low　temperature.　At　15°C,　the　effluent　ammonia　and　nitrite　of　S1　were　seriously　accumulated,　and　E1　could　maintain　a　stable　nitrogen　removal　effect　under　the　regulation　of　HRT.　The　population　diversity　was　maintained　in　the　immobilized　filler,　and　the　functional　bacteria　of　anammox　Candidatus　Kuenenia　was　effectively　enriched,　accounting　for　32.55%　in　E1.　The　results　of　this　study　provide　valuable　information　for　the　application　and　popularization　of　anammox　immobilized　filler.　©　2021　The　authors　and　IOS　Press.