Three　groups　of　reactors　of　the　same　specification,　respectively　referred　to　as　R1(operation　mode　of　continuous　flow　with　low　dissolved　oxygen　and　low　substrate),　R2(operation　mode　of　SBR),　R3(alternate　operation　mode　of　continuous　flow　and　SBR)　were　set　up　to　investigate　the　nitrite　nitrogen　accumulation,　pollutant　removal,　sludge　characteristics,　and　EPS　secretion　during　the　operation　period.　The　start-up　time　for　partial　nitrification　in　the　R1was　28days,　and　the　NAR　was　maintained　at　49.6%,　with　a　gradual　decrease　in　ammonia　removal　and　nitrite　concentration.　R2　achieved　partial　nitrification　in　12days,　and　the　NAR　was　maintained　at　95.6%,　but　it　was　reduced　to　82.6%　due　to　a　decrease　in　bacterial　activity　by　prolonged　FA　inhibition.　It　took　18days　for　R3　to　achieve　partial　nitrification,　then　R3　was　operated　for　90d,　with　a　NAR　of　92.3%　in　the　SBR　stage　and　90.2%　in　the　continuous　flow　stage.　The　ratio　of　NO2--N/　NH4+-N　in　the　effluent　of　R3was　basically　between　1.10　and　1.22,　and　the　sludge　had　a　relatively　dense　structure,　the　SVI　was　between　the　optimal　threshold　70and　100mL/g,　the　EPS　content　reached　54.63mg/gVSS,　the　SAOR　and　SNPR　were　6.7　and　2.5mgN/(gMLVSS∙h),　respectively.　The　above　research　indicates　that　the　alternate　operation　strategy　of　sequential　batch　and　continuous　flow　can　effectively　elute　NOB　while　ensuring　functional　bacteria　such　as　AOB,　achieving　stable　accumulation　of　nitrite.　©　2023　Chinese　Society　for　Environmental　Sciences.　All　rights　reserved.