To　achieve　advanced　nitrogen　removal　from　municipal　sewage　with　a　low　carbon/nitrogen　(C/N)　ratio,　a　novel　Sludge　Double　Recirculation-Anaerobic/Aerobic/Anoxic　process　(SDR-AOA)　was　developed　in　a　continuousflow　reactor.　Low　C/N　(3.19　in　average)　sewage　with　the　chemical　oxygen　demand　(COD)　concentration　of　180.14　mg/L　and　the　total　nitrogen　(TN)　concentration　of　56.19　mg/L　was　applied　for　long-term　treatment　in　the　SDR-AOA　process.　Results　showed　that,　the　average　nitrite　concentration　in　the　effluent　of　the　aerobic　zone　was　increased　from　0.15　mg/L　(phase　1)　to　16.46　mg/L　(phase　3),　and　the　nitrite　accumulation　ratio　(NAR)　remained　between　85.87%　and　94.85%　in　phase　3,　for　which　the　TN　removal　efficiency　was　increased　from　91.40%　(C/N:　5.14)　to　95.60%　(C/N:　3.19),　and　the　low　effluent　TN　concentrations　was　as　low　as　2.47　mg/L.　The　inhibitory　effect　of　anoxic　disturbance　on　nitrite　oxidizing　bacteria　(NOB)　might　contribute　to　the　effectiveness　of　partial　nitrification,　with　the　percentage　of　NOB　accounting　for　total　bacteria　being　declined　from　4.66%　(day　79)　to　1.51%　(day　135)　on　the　genus　level.　Nitrogen　mass　balance　analysis　demonstrated　that　27.77%　of　TN　was　removed　through　simultaneous　nitrification　and　denitrification　in　the　aerobic　zone,　while　the　remaining　TN　(62.25%)　was　removed　through　endogenous　denitrification　in　the　post-anoxic　zone.　Further　Illumina　MiSeq　sequencing　analysis　demonstrated　that　the　predominant　bacteria　were　Rhodocyclaceae,　Saprospiraceae　and　Comamonadaceae　on　the　family　level,　and　they　were　the　key　to　nitrogen　removal　processes.　In　the　end,　the　advanced　nitrogen　removal　was　realized　in　the　SDR-AOA　process　for　treating　low　C/N　municipal　sewage　through　the　successful　achievement　of　partial　nitrification　and　endogenous　denitrification.