In　order　to　improve　the　efficiency　of　shortcut　nitrification　by　entrapping　ammonia　oxidizing　bacteria,　the　technique　of　ammonia　oxidizing　bacteria　(AOB)　enrichment　culture　was　studied.　The　continuous　operation　method　was　used　to　inhibit　the　growth　of　nitrite-oxidizing　bacteria　(NOB)　by　free　ammonia,　at　the　same　time,　the　NOB　was　gradually　washed　out　of　the　system　through　the　technology　of　sludge　discharge.　Polyvinyl　alcohol　(PVA)　was　used　as　the　embedding　material　to　immobilize　the　ammonia　oxidizing　bacteria　after　enrichment　culture.　The　embedding　rate　of　the　reactor　was　8%.　The　ammonia　oxidation　rate　was　increased　by　improving　ammonia　nitrogen　loading　in　the　continuous　operation　mode.　The　results　showed　that　the　ammonia　oxidation　rate　(NH4+-N/VSS)　was　as　high　as　2.028　g·(g·d)-1　and　the　nitrite　nitrogen　accumulation　rate　was　stabilized　at　more　than　90%.　High-throughput　sequencing　analysis　was　conducted　on　the　bacterial　community　composition　before　and　after　enrichment　culture,　and　the　experimental　result　indicated　that　the　culture　diversity　of　raw　sludge　was　larger.　Nitrosomonas　and　Nitrospirae,　which　have　nitrification　function,　accounted　for　0.24%　and　2.7%,　respectively.　The　diversity　of　the　activated　sludge　decreased　significantly　after　the　enrichment　culture,　Nitrosomonas　(18%)　became　the　dominant　bacteria　whereas　Nitrospira　occupied　only　0.02%.　After　he　embedding　of　ammonia　oxidizing　bacteria,　the　shortcut　nitrification　was　realized　rapidly.　Finally,　the　shortcut　nitrification　rate　reached　50　mg·(L·h)-1　and　the　nitrite　nitrogen　accumulation　was　above　90%.　©　2017,　Science　Press.　All　right　reserved.