The　inhibition　of　the　on/off　aeration　time　ratio　on　nitrite　oxidizing　bacteria　(NOBs)　in　intermittent　aeration　is　the　key　to　accumulating　nitrite.　This　study　explores　the　stable　operation　of　nitrosated　granular　sludge　under　the　same　frequency　of　aeration　and　different　combinations　of　stop　exposure　time.　At　25-28,　aerobic　granular　sludge　was　inoculated　into　a　sequencing　batch　reactor　(SBR)　(R0)　and　acclimatized　to　nitrosated　granular　sludge　by　intermittent　aeration　and　dissolved　oxygen　(DO)　restriction.　The　effects　of　different　on/off　aeration　time　ratios　in　one　sub-aeration　cycle　(3　min:3　min;　4　min:2　min;　2　min:4　min)　on　the　performance　of　nitrosated　granular　sludge　were　analyzed　using　three　same　sets　of　SBRs　(R1,　R2,　and　R3).　Experiments　showed　that　the　nitrite　accumulation　rates　of　R1　and　R2　were　higher,　with　average　nitrite　accumulation　rates　of　89%　and　95%,　respectively.　The　nitrosation　performance　of　R3　was　poor,　and　the　nitrite　accumulation　rate　at　the　end　of　the　operation　cycle　was　only　57%.　The　results　showed　that　when　the　off-aeration　time　was　between　2　and　4　minutes,　the　longer　the　off-aeration　time　was,　the　more　stable　the　granular　sludge　structure　was;　hence,　a　good　nitrosation　performance　could　be　maintained.　When　the　off　aeration　time　was　less　than　2　minutes,　the　alternation　of　anaerobic　and　aerobic　environment　could　not　be　fully　realized,　which　resulted　in　the　sludge　tending　to　stay　in　an　environment　of　continuous　aeration.　Thus,　the　environmental　advantage　of　intermittent　aeration　was　lost;　the　NOBs　could　not　be　inhibited,　and　the　granular　sludge　was　disintegrated　thereby　leading　to　the　deterioration　of　the　nitrosation　performance.　Additionally,　the　longer　aeration　time　contributed　to　the　development　of　irregularly　shaped　particles.　The　longer　the　off-aeration　time　was,　the　higher　the　PN/PS　value　was,　which　was　beneficial　to　the　enhancement　of　the　hydrophobicity　of　the　particle　surface　and　the　sludge　settling　performance.　©　2020,　Science　Press.　All　right　reserved.