Abstract: In order to solve problems of insufficient carbon sources during biological denitrification and too much surplus sludge in wastewater treatment plant, a multi-aerobic-anoxic bio-film reactor was built to treat low ρ(C)/ρ(N) ratio wastewater in a community.The reactor could achieve its optimal results when flow distribution ratio was 3∶ 4∶ 3, HRT was 11 h, ρ(DO) was 4.0 mg/L, temperature was at 25℃, and reflux ratio R = 1.0.Under above conditions, when ρ(TN) , ρ(NH₄⁺-N) and ρ(COD) in raw water was 80~130, 75~100 and 260~400 mg/L, respectively, removal efficiency of TN, NH₄⁺-N and COD reached 80%, 95% and 91%, respectively, ρ(TN) in effluent was about 20 mg/L, ρ(NH4+-N) and ρ(COD) in effluent was dropped to below 5.0 mg/L and 30 mg/L, respectively.The results also showed that the sludge production rate was only 0.10, which was superior to other bio-film processes.So the effect sludge reduction was significant.