In　this　study,　feasibility　of　enhancing　ammonia-oxidizing　bacteria　(AOB)　activity　by　biological　addition　under　the　condition　of　temperature　fluctuation　and　further　improving　the　denitrification　effect　of　Single-stage　Partial　Nitrification　and　Anammox　(SPN/A)　process　in　municipal　wastewater　treatment　was　investigated.　Two　sequencing　batch　reactors　(SBR)　SBR1　and　SBR2　were　operated　in　intermittent　aeration.　The　controlled　temperature　was　reduced　from　30　gradient　to　15　(30,　27,　24,　21,　18,　15),　and　then　gradually　increased　to　30.Shortcut　nitrication　sludge　was　regularly　added　to　SBR2　to　enhance　AOB　activity　during　the　cooling　and　heating　process,　and　SBR1was　used　as　the　control　process.　The　results　showed　that　SBR1　and　SBR2　started　successfully　and　run　stably　without　shortcut　nitrication　sludge,　and　the　nitrogen　removal　efficiency　of　SBR1　and　SBR2　was　good　at　30.　When　the　temperature　was　dropped　to　15,　the　concentration　of　the　ammonia　nitrogen　in　effluents　of　of　SBR1　and　SBR2　were　36.38mg/L　and　33.10mg/L,　and　the　total　nitrogen　removal　efficiency　was　30.72%　and　35.76%,　respectively.　Both　rectors＇　efficiency　become　worse　in　low　temperature　settings,　SBR2　shown　a　better　cold　resistance　performance.　When　temperature　were　increased　gradient　back　to　30,　the　total　nitrogen　removal　rates　of　SBR1　and　SBR2　increased　back　to　52.43%　and　63.60%　respectively.　The　activity　of　bacteria　in　SBR1　and　SBR2　decreased　with　the　decrease　of　temperature,　but　the　AOB　activity　of　SBR2　was　higher　than　that　of　SBR1.　During　the　temperature　rising　stage,　the　activity　of　bacteria　in　SBR1　and　SBR2　both　increased,　and　the　inhibition　of　nitrite-oxidizing　bacteria　(NOB)　activity　in　SBR2　was　continuously　decreasing.　The　better　denitrification　performance　of　SBR2　was　suspected　because　when　the　AOB　activity　of　SBR2　was　enhanced,　more　nitrite　was　produced,　and　the　substrate　of　Anammox　was　increased,　which　resulted　in　the　higher　activity　abundance　of　Anammox.　Therefore,　it　was　conclude　that　the　AOB　activity　in　SPN/A　system　can　be　enhanced　by　biological　addition　at　low　temperature,　which　can　improve　the　resistance　performance　of　the　system　to　the　temperature　shocks　and　facilitate　the　recovery　of　denitrification　capacity.　©　2019,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.