In　order　to　inhibit　the　growth　and　reproduction　of　nitrite　oxidizing　bacteria　(NOB),　a　sequence　batch　reactor　(SBR)　(consisting　of　four　groups　of　reactors　R1∼R4)　was　used　to　run　the　PN1/PN2　system,　in　which　an　alternating　starvation/recovery　strategy　with　an　alternating　3　day　period　was　used　for　70　day　operation.　The　dissolved　oxygen　concentrations　in　the　starvation　phase　were　set　to　(1±0.5),　(2±0.5),　(3±0.5)　and　(4±0.5)　mg/L,　respectively,　and　the　selection　of　alternating　cycles　and　effects　of　dissolved　oxygen　conditions　on　the　activity,　sludge　concentration,　particle　size　and　extracellular　polymer　(EPS)　of　functional　bacteria　during　the　starvation　period　were　evaluated　to　define　the　stable　operation　of　the　nitrification.　The　results　show　that,　compared　with　ammonia　oxidizing　bacteria　(AOB),　NOB　was　more　sensitive　to　starvation,　the　activity　decay　rate　was　higher,　and　the　activity　recovery　rate　of　AOB　was　higher　than　that　of　NOB　in　the　first　days　of　the　recovery　period,　so　the　3　day　alternating　cycle　could　effectively　inhibit　NOB　and　retain　AOB　activity.　The　nitrous　accumulation　rate　(NAR)　of　the　four　groups　of　reactors　reached　73.36%,　84.43%,　91.21%　and　95.97%,　respectively,　followed　by　sludge　reduction,　but　the　sludge　concentration　of　R1∼R3　could　remain　stable　after　a　period　of　adaptation,　while　R4　showed　a　downward　trend.　The　alternating　starvation/recovery　strategy　allowed　the　system　to　gradually　eliminate　flocs　with　poor　sedimentation　performance,　while　the　sludge　with　good　sedimentation　performance　remained　in　the　reactor,　and　the　sludge　particle　sizes　in　the　four　reactors　on　the　70th　day　reached　190.69,　197.56,　207.69　and　153.56μm,　respectively.　Environmental　changes　stimulated　microorganisms　to　secrete　more　EPS,　so　the　EPS　content　of　the　sludge　in　the　four　groups　of　reactors　increased　at　varying　amplitudes.　Evidently,　the　alternating　starvation/recovery　strategy　can　stimulate　beneficial　changes　in　sludge　to　achieve　effective　NOB　inhibition　and　stable　NO2-N　accumulation.　©　2024　Chinese　Society　for　Environmental　Sciences.　All　rights　reserved.