Abstract: The Xiarihamu nickel-cobalt sulfide ore deposit in the East Kunlun orogenic belt is hosted in the No.1 mafic-ultramafic intrusion, with 1.18 million tons of Ni, 238,000 tons of Cu, and 43,000 tons of Co, which is the largest magmatic nickel-cobalt deposit found in the orogenic belt to date. Its geological background is obviously different from the large igneous province and the continental marginal rifts. The profound analysis of Xiarihamu is helpful to reveal the formation mechanism and metallogeny of the magmatic nickel-cobalt sulfide deposits in the orogenic belt, to provide instructions for the prospecting direction, and to expand the prospecting space of nickel-cobalt sulfide deposits in the East Kunlun orogenic belt. Through the research work of geological characteristics, mineralogy, and geochemistry of the Xiarihamu magmatic nickel-cobalt sulfide deposit and in combination with previous research results and practice of regional tectonic background, we found that the crustal sulfur contamination is the key factor for the sulfide saturation. The lithofacies with a high content of orthopyroxene are very favorable for the occurrence of rich ore bodies. we proposed that the Xiarihamu giant magmatic nickel-cobalt sulfide deposit is the result of the continental break-up related to the Paleo-Tethys ocean evolution. The regional fault provided channels for the mantle-derived magma. The ferruginous mafic-ultramafic intrusions along the Northern Kunlun Fault and the Central Kunlun Fault to the northwest and southeast of the Xiarihamu nickel-cobalt sulfide deposit have the potential to be the magmatic Ni-Co deposits.