The　stability　and　parameters　of　a　bio-ceramic　filter　for　completely　autotrophic　nitrogen　removal　were　investigated.　The　completely　autotrophic　nitrogen　removal　over　nitrite　(CANON)　reactor　was　fed　with　different　concentrations　of　ammonia　(400,　300,　and　200　mg　NIL)　but　constant　influent　ammonia　load.　The　results　showed　that　the　CANON　system　can　achieve　good　treatment　performance　at　ambient　temperature　(15-23　degrees　C).　The　average　removal　rate　and　removal　loading　of　NH4+-N　and　TN　was　83.90%,　1.26　kg　N/(m(3).day),　and　70.14%,　1.09　kg　N/(m(3).day),　respectively.　Among　the　influencing　factors　like　pH,　dissolved　oxygen　and　alkalinity,　it　was　indicated　that　the　pH　was　the　key　parameter　of　the　performance　of　the　CANON　system.　Observing　the　variation　of　pH　would　contribute　to　better　control　of　the　CANON　system　in　an　intuitive　and　fast　way.　Denaturing　gradient　gel　electrophoresis　analysis　of　microorganisms　further　revealed　that　there　were　some　significant　changes　in　the　community　structure　of　ammonium　oxidizing　bacteria,　which　had　low　diversity　in　different　stages,　while　the　species　of　anaerobic　ammonium　oxidizing　(anammox)　bacteria　were　fewer　and　the　community　composition　was　relatively　stable.　These　observations　showed　that　anaerobic　ammonia　oxidation　was　more　stable　than　the　aerobic　ammonia　oxidation,　which　could　explain　that　why　the　CANON　system　maintained　a　good　removal　efficiency　under　the　changing　substrate　conditions.