To　explore　the　influence　of　the　influent　flow　distribution　ratio　on　the　denitrification　efficiency　of　low-temperature　urban　wastewater　and　analyze　the　denitrification　of　multi-level　AO　coupled　flow　biochemical　process,　three-level　AO-coupled　biofilm　technology　was　used　to　treat　simulated　low-C/N　urban　sewage　at　a　temperature　of　10±1,　hydraulic　retention　time　of　8　h,　and　constant　air-water　ratio.　The　reactors　were　operated　under　three　conditions　of　inlet　water　ratios　of　5:4:4　(equal　volume　load),　3:2:1　(equal　hydraulic　retention　time),　and　25:15:6　(equal　sludge　load).　The　study　showed　that　the　multi-level　AO-coupled　displacement　biochemical　process　has　a　good　removal　efficiency　with　respect　to　low-temperature　and　low-C/N　wastewater.　The　pollutant　removal　efficiency　is　the　highest　when　the　ratio　of　the　influent　is　3:2:1　and　the　average　removal　rates　of　COD,　NH4+-N,　and　TN　are　87.44%,　96.63%,　and　76.81%,　respectively.　Further　studies　on　the　law　of　nitrogen　migration　and　transformation　showed　that　the　main　factors　constraining　the　nitrogen　removal　under　three　conditions　were　the　nitrification　efficiency　at　each　levels,　the　ratio　of　3:2:1　influent　reasonably　distributing　the　influent　load,　and　the　nitrification　efficiency　at　each　level　exceeding　85%,　creating　favorable　conditions　for　denitrification　and　leading　to　a　higher　denitrification　efficiency,　while　the　system　has　the　highest　total　biomass.　The　research　results　enrich　the　theory　of　multi-level　AO　cryogenic　removal　of　nitrogen　and　provide　references　for　engineering　designs　and　applications.　©　2018,　Science　Press.　All　right　reserved.