Compared with other traditional nitrogen removal technologies, the Anaerobic ammonium oxidation (Anammox) process is a new nitrogen removal process with the advantages of no additional carbon source, energy saving and emission reduction. However, in the practical application process, it is difficult to start up quickly due to sludge loss. Anammox granular sludge (AnGS) can improve the efficiency of nitrogen removal and ensure the long-term stable operation of the Anammox process, the reinforcement of AnGS by adding iron is one of the most widely studied, economical, and practical measures at present. This paper briefly describes the characteristics, metabolic pathways, and aggregation mechanism of Anaerobic ammonium oxidation bacteria (AnAOB), focusing on combining the mechanism of iron regulation of AnGS in terms of regulating the synthesis of enzymes and the expression of functional genes, accelerating the enrichment of functional bacteria, supplying granular sludge condensation nuclei, promoting the secretion of extracellular polymer (EPS), and strengthening the systemic group induction, to provide theoretical guidance for the development and application of iron-enhanced Anammox technology.