The aim of this paper is to study sea level changes on the impact of manganese ore and its distribution. The depositional systems and spatial distribution as well as temporal evolution of the manganese-bearing intervals in Ladinian stage of Middle Triassic in Southeast Yunnan are analyzed based on the lithofacies associations, sedimentary structures and biological fossils from stratigraphic sections. Ladinian sequence stratigraphic frameworks is established according to identification of sequence and system tracts surfaces under different paleogeographical backgrounds. The writers summarize spatial superimposed relationships and formation mechanism of manganese deposits, and preliminary analyse the manganese ore formation model. It is suggested that low deposition rates period of rapid sea-level rising is most conducive to manganese precipitations, and manganese ore-forming model is established in the study area: regional sea-level fall, manganese material from tectonic activity or leaching weathering, enrich in the depression or low-lying land, with next rapid sea-level rise，promote these position more closed and poor oxygen，further enrichment of manganese，finally mineralized under the biochemical process of bluegreen algae.