To　characterize　the　microbial　community　in　anaerobic　ammonia　oxidation　(ANAMMOX)　biofilter　and　to　apply　this　technology,　techniques　of　scanning　electron　microscopy　(SEM),　denaturing　gradient　gel　electrophoresis　(DGGE),　cloning　and　sequencing　were　utilized　to　study　the　community　structures　in　two　up-flow　ANAMMOX　biofilters,　which　were　operated　stably　at　low　temperature　(15.0-16.5°C).　The　results　of　SEM　showed　that　the　filamentous　bacteria　were　just　found　within　ceramic　packing　B1　biofilter.　Spherical　bacteria　had　more　densely　distribution　in　volcanic　packing　B2　biofilter　than　that　in　B1　biofilter.　Bacterial　DGGE　results　showed　that　there　were　some　differences　between　B1　and　B2　microbial　species　and　the　population　similarity　was　68.1%,　and　B2　reactor　had　higher　bacteria　richness.　However,　the　type　of　anammox　bacteria　existence　in　two　reactors　was　the　same.　The　sequences　of　bacteria　and　ANAMMOX　16S　rRNA　identification　revealed　that　Candidatus　Kuenenia　stuttgartiensis　occurred　in　two　ANAMMOX　bioreactors.　It　was　helpful　to　apply　ANAMMOX　technology　at　low　temperature　(15.0-16.5°C)　through　Candidatus　Kuenenia　stuttgartiensis　enrichment,　with　the　form　of　biofilter　reactor　filled　with　volcanic　rocks.