Abstract:The anaerobic ammonia oxidation (anammox) reaction with nitrite as an electron acceptor and nitrogen as a product is mediated by bacteria which belong to Planctomycetales. AnAOB are widely present in marine, freshwater and terrestrial ecosystem, it also can be found in some other extreme environments. In this study, we reviewed the most new research advance on taxonomy, characteristics, metabolism, distribution, biotechniques used for the analysis of AnAOB and application. Finally, we discussed some questions exiting in this field and prospected future research of anaerobic ammonium oxidation microorganisms.