Anaerobic ammonium oxidation (ANAMMOX) is a process that the bacteria of anammox convert NH4+-N into N2 with the NO2?-N as the primary electron acceptor under anaerobic condition. It is considered as a very promising nitrogen removal technology in future, because of its cost effectiveness and environmental friendly characteristics. Here, we review its mechanism, influence factors, application situation and the bacteria of anammox. Some suggestions are given for the development of anammox application in wastewater treatment.