Based on years of exploration and research, there are three superficial deposits of Xixibao manganese deposit, Yangjiawan manganese deposit, Lijiawan manganese deposit, making up a new pattern of “Manganese Triangle”, in which Yangjiawan manganese deposit is a medium-large one. Geological and geochemical characteristics of manganese-bearing rock series of Yangjiawan manganese deposit indicate that in manganese-bearing rock series exists volcanic material such as tuff, and mineral association of pyrite, barite and calcimangite, which shows a hydrothermal origin. In addition, δEu(0.49~0.71), δCe(0.94~1.25) and Ce/La-La/Yb diagrams also show features of hydrothermal participation.Besides, δ13CPDB and δ18OPDB of the manganese deposit range from -3.80‰ to -4.17‰ and from -6.95‰ to 8.78‰, respectively. In conclusion, the authors consider that Yangjiawan manganese deposit is of hydrothermal genesis.