Hydrolization and stabilization of iron in environmental media are usually impacted by iron bacteria and their metabolization substances. Iron bacteria are commonly present in natural environments and can use ferrous iron as energy sources for their growth. Bacteria producing extracellular polymeric substances (EPS) mainly including polysaccharides and proteins can combine ferrous iron. The combined ferrous iron can further be bio-oxidized and precipitated into iron minerals. Moreover, bacteria/EPS can catalyze Fe²⁺ bio-oxidization and promote Fe assembly. The biological iron minerals have good chemical properties such as surface adsorption and oxidization-reduction, and good environmental attributes including effective fixation of heavy metals and radioactive nuclides, and catalytic degradation of organic contaminations. So these biological iron minerals play an important role in the study of environmental and biological mineral materials as well as in the treatment of polluted circumstances. Based on the key regulation action on bio-mineralization of iron by bacteria/EPS, the authors introduced iron bacteria and their biological mineralization characteristics in the environment, and mainly described the composition, structure and attribute of EPS exuded by iron bacteria as well as its key role in iron bio-mineralization. Meanwhile, the environmental significance of iron-bacteria/EPS and biogenic iron minerals was also discussed in brief.