The Tongchang copper- iron deposit is an ideal representative deposit from the Mian- Lue- Ning ore- cluster region. The ores from the Tongchang copper- iron deposit can be divided into three types: magnetite ores, sulfide- bearing magnetite ores and sulfide ores. Systematic petrography and ore mineralogy research shows that the ore minerals are mainly composed of magnetite, chalcopyrite, pyrite and pyrrhotite; the ores have euhedral- subhedral- anhedral crystalline grained texture, metasomatic relict texture and poikilitic texture, and have massive, disseminated, vein and banded structures. The wall- rock alteration of the upper copper orebodies is characterized by silicification, carbonation and biotitization, and the altered mineral assemblages are mainly composed of quartz, calcite and biotite, showing the characteristics of potassic alteration. Moreover, the wall- rock alteration of the lower iron orebodies is characterized by serpentinization, talcification, tremolitization, carbonation and chloritization. The altered mineral assemblages are mainly composed of serpentine, talc, tremolite, calcite, dolomite, siderite, chlorite, biotite and a small amount of apatite, showing the characteristics of sodic alteration. The contents of TiO 2 and Al 2O 3 in magnetite are lower than 1.72% and 1.81%, respectively, showing the characteristics of hydrothermal magnetite. Combined with the field geological phenomena of the copper ore veins intersecting the Tongchang diorite and the sharp contacts between them, the evidence indicates that the formation of the Tongchang copper- iron deposit is closely related to hydrothermal activity. Moreover, the Tongchang copper- iron deposit was formed in the Caledonian period of the Early Paleozoic, when the Mian- Lue- Ning area was in an expansion environment, similar to the formation environment of the iron oxide- copper- gold (IOCG) deposit. By comparing the geological characteristics, mineralization and alteration features, mineral assemblages, mineral geochemical characteristics and the geotectonic background of the typical IOCG deposit, it is tentatively proposed that the Tongchang copper- iron deposit should belonged to the IOCG deposit.