In　order　to　start　up　astable　simultaneous　anammox　and　heterotrophic　denitrification　process　to　treat　domestic　sewage,　the　experiment　was　carried　out　at　different　ammonia　nitrogen　removal　of　the　load　(ANR).　During　the　operation　period,　the　variation　of　ammonia　nitrogen　(NH4+-N)nitrite　nitrogen　(NO2--N)　and　nitrate　nitrogen　(NO3--N)　and　dynamics　activities　of　functional　microbes　were　investigated　to　elaboratemain　factors　for　the　SAD　process.　The　results　showed　that　the　reactor　could　treat　domestic　wastewater　containing　100~150　m　g/L　COD　when　the　ANR　was　during　0.27~0.40　kg/(m3　·d)　and　it　could　treat　domestic　wastewater　containing　100~200　m　g/L　COD　stably　when　the　ANR　was　0.85　kg/(m3　·d)　The　reactor　could　start　up　stable　SAD　process　if　the　ratioof　ananmmox　bacteria　dynamics　activity　(μNH4+-N)with　heterotrophicbacteria　(μCOD)　and　denitrificationbacteria　(μNO3--N)　was　within　reasonable　limits.　The　anammox　bacteria　activity　was　increased,　meanwhile　the　heterotrophicbacteria　and　denitrificationbacteriaactivity　were　decreased　when　the　hydraulic　retention　time　(HRT)　was　reduced.　According　to　the　cycle　experiments,　the　simultaneous　anammox　and　partial　denitrification　process　©　2017,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.