Two-stage　biological　aerated　filter　was　used　for　domestic　wastewater　treatment.　The　hydraulic　loading　rate　of　A-stage　limited　to　9.17　m3/(m2·d),　15.59　m3/(m2·d)　and　22.01　m3/(m2·d)　respectively　and　the　ratio　of　air　to　water　was　6　to　1,　while　the　mtio　of　air　to　water　was　2　to　1　at　B-stage,　and　temperature　was　kept　in　the　range　of　18-20°C　throughout　the　experiment.　After　3-month　operation,　the　result　shows　that　stable　and　advanced　effluent　with　the　results　of　sCOD　3-N　＜　4.0　mg/L,　SS　＜　10　mg/L　at　steady　state　has　been　abtained,　and　the　chlorinated　effluent　well　meets　the　quality　standards　of　water　reused　for　toilet　flushing,　street　flushing,　fire　fighting　and　urban　greening;　Meanwhile,　the　sCOD,　ammonium,　total　nitrogen　and　total　phosphorous　of　the　effluant　also　has　been　kept　at　lower　level　under　the　condition　of　non-steady　state　such　as　loading　rate　adjustment　or　backwashing.　Moreover,　it　is　to　maintain　a　stable　operation　of　the　BAF　system,　pre-treatment,　suitable　backwashing　rate　and　good　start-up　conditions　are　quite　necessary.