Simultaneously　partial　nitrification,　anammox　and　denitrification　(SNAD)　process　was　used　for　treating　domestic　sewage　in　a　membrane　bioreactor　(MBR).　Domestic　sewage　was　gradually　pumped　into　the　system,　removal　trend　of　the　pollutants　were　evaluated　via　the　changing　of　operational　HRT　and　air　flow.　The　nitrogen　removal　pathway　was　analyzed　via　the　mass　balance　analyze　studying,　and　microbial　characteristics　via　clone-sequencing　detection.　Results　suggested　that　a　simultaneous　removal　of　C,　N　and　SS　was　achieved　in　the　system,　with　the　nitrogen　removal　rate　to　0.65　kg/(m3·d),　effluent　ammonia　below　10　mg/L;　COD　removal　efficiency　to　87%,　effluent　COD　below　50　mg/L;　turbidity　removal　to　99%,　effluent　turbidity　below　1　NTU,　and　SS　below　10　mg/L,　which　met　the　demand　of　the　first　grade　A　standards　of　Urban　Sewage　Disposal　Plant　Contamination　Integrated　Discharge　Standard　(GB18918-2002).　Denitrification　contributed　to　12%　nitrogen　removal　while　(completely　autotrophic　nitrogen　removal　over　nitrite,　CANON)　contributed　to　88%,　and　AOB,　anammox　and　denitrifiers　coexisted　in　the　reactor.　©,　2015,　Harbin　Institute　of　Technology.　All　right　reserved.