Abstract: The Xiaerchulu gold deposit is tectonically located in the Late Paleozoic active continental margin in the Bainaimiao-Wenduermiao ancient landmass. The wall rocks of the deposit involve the metamorphic series of Baiyinbaolage Formation and the biotite granite of Early Triassic. The orebodies occur in the structural fracture zones, controlled by N-S-trending faults. The Au-bearing quartz veins are characterized by expanding, brenching and merging. Study on the mineral assemblage, structure and texture of the ore shows that the mineralization is related to the alterations of silicification, phyllication, pyritization and molybdenitization. The metallogenesis took place under the extensive geodynamic environment. The ore-controlling structures moved in multiple stages. The gold deposit genetically belongs to post-magmatic hydrothermal fluid type.