Heqing manganese deposit is located in the southwestern margin of Yangtze platform in Yunnan Province, China. Carbon and oxygen isotopes indicate that Songgui Formation which is the main ore bearing stratum experienced one transgression and another long-term regression. The paleotemperature derived from oxygen isotopes are higher due to the exchange of oxygen isotope between biological (algae) metabolites and seawater, changes in paleoclimate and sea depth. With uplifting of Yangze platform continuously and climate changing from humid, hot into arid gradually, the manganese ores were formed accompanied by falls in sea level.