Abstract: The Tiemulike iron deposit is one of the deposits with highest-grade magnetite in the Awulale metallogenic belt and is hosted in volcanic rocks of the Carboniferous Dahalajunshan Formation. Its wall rocks have experienced a little alteration, mainly chloritization and epidotization. According to the ore fabrics and microscopic observation, mineralization of the deposit can be divided into four ore-forming stages. Since very insufficient work has been done in this aspect, the genesis of the deposit fails to reach an agreement. Magnetite and hematite electron microprobe analyses show that the deposit was genetically closely related to the magmatic-hydrothermal system. Pyroxene and amphibole electron microprobe analyses show that alteration of pyroxene is very weak, with only slight actinolitization of hornblende. Sulfur isotope from pyrite (0.1‰~2.9‰) indicates that the metallogenic material might have been derived from deep mantle. Oxygen isotope from magnetie (-2.7‰~0.5 ‰) shows that late epithermal ore-forming process played an important role in the reformation of the early magnetite. Combined with the geological characteristics of the metallogenic belt, this paper suggests that the Tiemulike iron deposit was mainly formed by the magmatic-hydrothermal mineralization system; after the formation of a large quantity of magnetite, the remaining small amount of fluid was mixed with ocean water, resulting in a epithermal alteration process and leading to the filling of hematite and in the magnetite ore.