Abstract: The Hongqiling CuNi ore deposit is located to the northern flank of a contacting zone (the Huifahe fault systems) between the North China platform and the JilinHeilongjiang syncline system. There are over 30 mafic and ultramafic intrusions in the area and CuNi sulfide ore bodies were found in No.1 and No.7 ultramafic intrusive bodies which exhibit obvious zoning and cumulate texture. CuNi ore bodies, being in the shape of plate, vein and pocket, were found in the olivinepyroxenite facies at the base of the ultramafic intrusions. Petrological and geochemical studies indicate No.7 intrusion was formed mainly by flow differentiation　while the No.1 intrusion by gravity differentiation; the source of magmas are of tholeiitic origin while the massores are of the products of pressure injecting; the addition and mixing of later magmas introduced more oreforming materials; the degree of immiscibility of sulfides was controlled by volatile components. This CuNi mineral deposit was derived from deep magma segregation with the oreforming age at Indosinian period.

Key words: ultramafic rocks, igneous cumulate texture, CuNi sulfide deposit, Hongqiling