Biological autotrophic denitrification based on anaerobic ammonium oxidation（ANAMMOX）has been considered as the most economical way in biological sewage treatment processes for nitrogen removal presently.Using bio-ceramic filter with volcanic activity，urban sewage pilot study was carried out at room temperature (8—25℃) under the condition of low NH+4-N (60—90 mg·L-1)，by changing the operating conditions such as aeration etc.After three stages—nitrification hanging film，preferred nitrite bacteria and culturing anaerobic ammonia-oxidizing bacteria，CANON（completely autotrophic ammonium removal over nitrite）process is realized in biofilter.The results show that DO control can be the main factor for controlling reactor startup.Through combined treatment of aeration at the top of water column in biofilter and internal recycling of treated water with oxygen，the control of DO concentration in the biofilm system is easily achieved.Furthermore，the reaction cycle can be judged from the change of pH value in the run process and its second-jump is a signal of end of reaction period.