A　modified　two-stage　anammox　process　was　constructed　and　achieved　advanced　nitrogen　removal　from　municipal　wastewater.　The　first　stage　was　Partial　Nitrification　(PN),　in　which　nitrite　accumulation　rate　was　over　95%　by　controlling　dissolved　oxygen　concentration　(＜　1　mg/L)　and　aeration　time　(90-120　min).　The　second　stage　was　simultaneous　anammox　and　denitrification　(SAD),　in　which　the　reactor　was　fed　with　the　effluent　of　the　first　stage　and　a　part　of　raw　wastewater.　The　effluent　total　inorganic　nitrogen　(NH4+-N,　NO2--N　and　NO3--N)　was　only　1.6　+/-　0.8　mg　N/L　and　the　nitrogen　removal　efficiency　reached　97.1%.　The　proportion　of　anammox　in　nitrogen　removal　was　up　to　73-82%　and　Candidates　Brocadia　was　the　main　anammox　genus　accounted　for　8.0-2.2%.　And　partial　denitrification　occurred　with　the　appearance　of　Thauera　(0-1.0%).　The　PN-SAD　process　is　an　energy-saving　treatment　for　municipal　wastewater　with　a　total　hydraulic　retention　time　of　6　h.