Abstract: Xixibao manganese deposit in Songtao is another concealed super-large manganese deposit which was found by the theory of ancient natural gas seepage sedimentary-type manganese ore-forming and exploration model in recent years.The orebody occurs as quasi-lamellar and stratiform structure,with huge thickness and extension scale.The prismatic comparison of manganese-bearing strata of Liangjiehe Formation in Xixibao manganese mining area and the sedimentary thickness isogram of manganese-bearing rock,together with the study of rhodochrosite orebody and Datangpo Formation,reveals that the long axis of Xixibao graben basin which controlled the formation and distribution of super-large manganese deposit is 60 degrees NE but not in the strike direction of NE at 30 degrees.The characteristics of center phase,transition phase,marginal facies and other ancient natural gas seepage eruption sedimentary microfacies are clear,with two seepage eruption sedimentary centers.With big exploration potential,Xixibao graben basin is a new super-large manganese deposit of world class and is predicted to possess the total manganese resources twice as much as its present controlled manganese resources.