A　novel　swimming　bed　reactor　with　no　reflux　which　suit　for　small　scale　wastewater　treatment　was　developed.　The　performance　of　the　reactor　for　treating　domestic　wastewater　was　investigated.　Steady　removal　effect　with　71.75%　of　average　COD　removal　rate　was　achieved　in　hydraulic　retention　times　(HRT)　of　20.74h　∼　4.30h.　When　hydraulic　retention　time　(HRT)　was　at　8.12h　with　average　NH4+-N　volumetric　loading　of　0.25　kg/(m3.d),　78.5%　of　average　NH4+-N　removal　rate　was　obtained.　In　the　optimal　condition　with　pH　of　6.7∼7.7,　92.2%　of　average　NH4+-N　removal　rate　was　obtained.　Presence　of　protozoa　and　metazoa　on　the　biofilm　were　observed　and　steady　food　chains　was　contributed　to　the　sludge　reduction,　0.2840　of　sludge　yields　(MLSS/CODremoved)　was　obtained　in　the　experiment.　©　2011　IEEE.