The conventional method of nickel converter slag dilution is reduction–sulfurization by adding coal and pyrite into the slag. In this study, the effect of sulfur content in the initial slag ((pct S)0) on the slag dilution process was determined by producing metal, which is significantly different from the conventional method producing matte. Analysis of the nickel converter slag showed that nickel, cobalt, and copper were mainly present in the form of sulfides, which are difficult to separate from the slag. The NiO, CoO, and Cu2O in the slag are easily reduced into metal using carbon, while the presence of sulfur inhibits the reduction reaction. In a vertical resistance furnace, the desulfurized slags with different sulfur contents were reduced using carbon. The sulfur distribution rate increased with the decrease in (pct S)0; the distribution of nickel, cobalt, and copper decreased with the decrease in (pct S)0. The nickel recovery rate increased with the decrease in (pct S)0, while (pct S)0 almost had no effect on the recovery of iron, cobalt, and copper. The distribution rates of sulfur, nickel, and copper increased with the increase in mole ratio of carbon to reducible oxygen (nC/nO), while the distribution rate of iron and cobalt decreased with the increase in nC/nO. In addition, the recovery rates of iron, nickel, cobalt, and copper increased with the increase in nC/nO.