The　completely　autotrophic　nitrogen　removal　over　nitrite　(CANON)　process　is　an　important　component　of　energy　self-sufficient　sewage　treatment　plants,　and　the　use　of　aerobic　granular　sludge　is　a　profitable　choice　for　the　CANON　process.　In　this　study,　the　performance　and　microbial　characteristics　of　CANON　granular　sludge　were　investigated　for　treating　synthetic　and　mainstream　domestic　sewage.　The　average　nitrogen　removal　rate　(NRR)　was　3.22　kg　Nm(-3)　d(-1)　during　the　high-rate　operating　period　with　high　MLSS　(4.09　g　L-1)　and　DO　(similar　to　1.0　mg　L-1)　for　treating　synthetic　sewage.　When　the　influent　was　mainstream　sewage,　the　average　NRR　was　1.11　kg　Nm(-3)　d(-1).　The　effluent　nitrate　concentration　was　very　low,　and　nitrate　build-up　was　not　found.　High-throughput　pyrosequencing　results　indicated　that,　Nitrosomonas　and　Candidatus　Brocadia　were　the　dominant　genus　in　ammonia　oxidizing　bacteria　(AOB)　and　anaerobic　AOB　(AAOB),　respectively.　The　proportions　of　AOB　and　AAOB　decreased　during　mainstream　sewage　treatment,　but　the　reactor　maintained　good　performance.　The　results　confirmed　the　feasibility　of　using　CANON　granular　sludge　for　treating　mainstream　sewage.