Abstract: Based on the principles of sedimentology, coal geology and paleogeography, the paper studied the lithologic characteristics of rocks in Jianshan formation, including color, structure and primary sedimentary structures. Combined with spatial configuration research and geological maps, the group identified two sendimentary facies from Jianshan formation, namely littoral facies and neritic facies, where littoral facies can be subdivided into sediment subfacies of sandy coast without barrier and the barrier island -lagoon sediment subfacies. The barrier island -lagoon subfacies of semi-restricted bay formed in 2nd layer of 2nd section in Jianshan formation, mesoproterozoic erathem Changcheng system is the main environment of manganese mineralization in the studied area, controlling the formation and distribution of manganese. During the process of mineralizing, the sea was shallow and the sedimentary environment was stable, which was advantageous to the enrichment of manganese oxide ore. Consequently, a set of layered or stratiform-like oxidized manganese deposits was formed, with major ores being pyrolusite, psilomelane and limonite. After metallogenesis, regional metamorphism took place under the effect of the dynamic force and heat, transferring the hematite into magnetite. The mineral composition is thus rearranged with obvious banded structure. The surrounding rock of seam roof and floor is silty slate, and the genetic type is marine sedimentary-metamorphose Mn deposit.