By chemical composition analysis, X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) and other measurements, the process mineralogy of Jinchuan nickel slag in a settlement furnace was studied, including the mineral composition, structure, embedded features, distribution of Fe, Ni, Cu, and Co. The results show that the phase composition of the slag includes hortonolite and glass, a few Cu-Ni sulphide, chalcocite and magnetite. The structure of the slag is single, and the Cu-Ni sulphide is distributed in the silicate irregularly. The irons are mainly located in the hortonolite, nickel and copper are mainly located in the Cu-Ni sulphide, and there is no independent minerals about cobalt, which is in the form of isomorphism in other minerals. The recovery of valuable metals from the slag can use deep reduction process or hydrometallurgy.