Because of its unique advantage,Anaerobic ammonia oxidation has become one of frontiers of biological denitrification research.Research shows that,two main types of anaerobic denitrification process of ANAMMOX and denitrification may exist in ANAMMOX reactor simultaneously.The theory study of denitrification and ANAMMOX of existing at the same time was mainly expounded,and the existing problems and future research direction were pointed out.