The　performance　of　organics　and　nitrogen　removal　as　well　as　sludge　reduction　were　investigated　in　a　novel　catching　bed　biofilm　reactor　which　applies　to　decentralized　wastewater　treatment.　The　results　indicate　that　the　average　removal　rate　of　COD　reached　to　81.7%　with　different　hydraulic　retention　time　(HRT);　Even　HRT　was　only　2.94h,　the　average　volumetric　loading　of　NH　4+-N　and　TN　were　0.65　kg/(m3·d)　and　0.81　kg/(m3·d),　the　removal　efficiencies　of　NH4+-N　and　TN　reached　the　climax　about　74.7%　and　65.2%.　Protozoa　and　metazoan　were　observed　on　the　biofilm　and　suspended　sludge.　The　sludge　yield　was　roughly　achieved　as　0.1465Kg　MLSS/KgCODremoved,　which　was　only　about　50%　of　the　conventional　aerobic　processes.　©　2009　ASCE.