Abstract: By field geological survey, 4 silver-gold orebodies and 16 faults or fracture zones are found in the Nanwanzi silver-gold deposit in Inner Mongolia. Combined with laboratory sample testing results and comprehensive data, the geological characteristics, genesis and prospecting indicators of the silver-gold deposit are studied on the basis of geological structures of the orefield, and related petrology and mineralogy of the deposit. The Nanwanzi silver-gold deposit is occurred mainly in the tuffite breccia, breccia-bearing tuff and effusive rhyolite of Elitu Formation, and the orebody is mainly controlled by F1, F2, F12 and F13 faults. The orebody is of ferromanganic quartz vein type, with metal minerals of pyrolusite, psilomelane, pyrite, goethite, lepidocrocite and tetrahedrite. The ores are in hypidiomorphic-allotriomorphic granular texture, dominated by sparse disseminated structure and massive structure. The orebodies are in podiform lenticle, lenticular, pisolitic and thin-bedded shapes. The study shows that there is no obvious associating relationship between gold and silver. The deposit genetically belongs to meso-epithermal alteration type. The ferromanganic quartz vein is the direct prospecting indicator.