Abstract: The Hongqiling nickel orefield is a significant concentrated mineralization zone of copper-nickel sulfide of magmatic type in China. Previous exploration has found middle-sized copper-nickel deposit in No. 1 rock body and large scaled copper-nickel deposit in No. 7 rock body. Presently, a large and thick nickel-cobalt ore body is discovered in the deep of No. 3 rock body. With studies on the lithology, microelements and REE geochemistry of the rock body, the genesis of the deposit is discussed. It is concluded that there is an affinity between the ore rock body and the mafic-ultramafic rock. The deposit is genetically formed by deep magmatic liquation and differentiation.