Anaerobic　fluidized　bed　membrane　bioreactor　(AFMBR)　with　simulated　domestic　wastewater　was　studied　at　room　temperature.　With　the　influent　COD　of　270mg/L,　AFMBR　system　operated　through　acclimation　and　enrichment.　The　effluent　SCOD　could　remain　stable　under　30mg/L.　With　the　decrease　of　temperature　in　winter,　the　effluent　SCOD　was　between　30and　40mg/L　as　the　activity　of　anaerobic　transformation,　such　as　methanogenic　bacteria,　in　the　system　might　be　inhibited,　but　the　level　A　Emission　Standard　could　still　be　meet.　The　total　methane　conversion　amount　was　about　0.182L/g　CODR,　about　45%　of　the　influent　COD　conversion　to　methane.　The　sludge　production　of　the　AFMBR　system　for　218days　operation　continuously　was　0.071g　VSS/g　COD,　which　was　much　lower　than　the　typical　aerobic　one.　As　for　the　net　energy　output　of　the　system,　if　the　gaseous　methane　production　was　only　considered,　the　energy　demand　for　mechanic　power　could　be　met　when　the　HRT　was　reduced　to　10h;　if　all　the　methane　production　was　taken　into　account,　the　energy　demand　could　be　met　when　the　HRT　was　reduced　to　20h.　When　the　HRT　was　reduced　to　10h,　the　energy　output　was　twice　over　the　energy　demand.　Thus,　the　AFMBR　system　had　great　potential　as　an　energy　positive　wastewater　treatment　system.　©　2018,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.