Iron is an essential trace element for most organisms and plays a key role in health and disease, particularly in host-pathogen interactions. In bacteria, the intracellular iron concentration serves as a critical signal in not only controlling the expression of iron transport systems with high affinity, but also regulating the production of toxin and other important virulence factors. However, the overload of iron can lead to lethal cytotoxicity. Therefore, iron homeostasis is strictly regulated in most organisms, of which the iron binding global regulator, Fur (ferric uptake regulator) plays a pivotal role in the regulation of intracellular iron concentration. This review summarized the progress in the study of four aspects of Fur, including the composition of FUR superfamily, the structures of the Fur proteins and their difference, the regulation network of Fur, as well as its regulatory mechanism, thereby to provide insights for further research of Fur and iron homeostasis.