///The Pobei mafic-ultramafic belt is an impotant Ni-Cu sulfide metallogenic prospective province in Beishan area, eastern Xinjiang. About 20 intrusions were recognized along the fault in this area and almost all the intrusions are associated with Ni-Cu sulfide deposits. The Hongshishan mafic-ultramafic complexs are located in the eastern part of the Pobei mafic-ultramafic belt and the southern part of the Baidiwa-Yunihe fault in this area. They intruded into quartz schist of the Lower Carboniferous Hongliuhe Formation. They are mainly composed of dunite, peridotite, troctolite, pyrox-enite, olivine gabbro, gabbro and diorite. The fractionation of olivine and contamination by crustal material probably triggered the sulfide saturation and segregation and the Ni-Cu-(PGE) mineralization as well. The intrusions were generated from the magma that had undergone crystallization differentiation of olivine and segregation of sulfides.