The manganese deposit in the Ladinian Falang Formation of the Middle Triassic,produced in the Southeast of Yunnan.In research areas both have Mn oxide and Mn carbonates,which is sedmentry no obviously metamorphism and most of them have bioclast. Concentric rings structure are obviously observed in oolitic and pisolitic manganese ores. The thin sections from manganese ore samples are systematically observated from typical deposits in Dounan,Yanzijiao,Laowu and Tujichong. The microstructures of oolitic and pisolitic ores are detailed described on the observation of microscope. It is suggested that these concentric laminar structures in manganese deposits are origin of blue-green algae microorganism and similar to common oncolitic structures. They have nucleus and encrustation fabric that can be compared with present Fe—Mn nodule in modern deep ocean environment. The preliminary study results show that Mn enrichment in this region probably relative to microorganism activity,also finding biodetritus in the manganese ore,which means manganese ore close to the redox level.