This paper explores the metallogenic geological background, sedimentary minerals, trace elements and C and 0 isotopes of the Nanhuaian manganese deposits in southeastern Guizhou Province. The results show that the ore-forming materials mainly come from deep crust, and are related with volcanism and exhalation. The sedimentary manganese-bearing basin was controlled by syngenetic deep fault zones. The early strong tectonic and hydro- thermal activities resulted in hot water mineralization traces of ore beds and its minerals, and manganese deposits have part of hot water mineralization characteristics. However, according to the ratios of the trace elements in Mn-bearing series, and the characters of geochemistry of the oxygen isotope and the carbon isotope, it can be inferred that the chemical action and the biochemical action dominate the sedimentary processes of the manganese ores in this area.