Abstract： The Olympic Dam polymetallic iron oxide breccia complex (referred to as IOCG type) deposit is currently the largest known uranium deposit in the world and one of the top three copper deposits in the world. The uranium resource is 2 171 359 t with a grade of 0.02%, which are under mining. The uranium mineralization occurs in a large, complex funnelshaped hydrothermal breccia body, which is called “Olympic Dam Breccia Complex (ODBC)”. ODBC is controlled by the structure and formed in the Roxby downs granite, Atype granite, intruded in the early Mesoproterozoic. The formation environment of the breccia complex is a highlevel phreatic magmatic volcanic mechanism similar to the Maar lake. Uranium mineralization is spatially related to hydrothermal alteration assemblages rich in hematite and oxidation. The main uranium mineral is uraninite, with a mineralization age maybe later than 1 590 to 1 580 Ma. The rift block caused by extensional movement is favorable to preserve the hematite richuranium rich IOCG type deposit formed near the surface, while the rising area around it shows the characteristics of deeper, magnetite rich and uranium poor IOCG type deposits.