Abstract: 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 ℃ throughout the experiment.After 3-month operation,the rosult shows that stable and advanced effluent with the results of sCOD<30 mg/L,NH₃-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.