<p>Magnetic separation methods have been widely applied in the pretreatment of environmental samples. In this study, six types of soil samples from industrial areas, farmlands, residential areas, forest lands, green belts, and parks in Nanjing City underwent magnetic separation, forming strong and weak magnetic fractions. The magnetic susceptibility indicators (χ_lf, χ_fd%, and χ_fd) and the contents of heavy metal elements (Cd, Cu, Pb, and Zn) were then determined. The magnetic susceptibility of the strong magnetic fraction (450.7 × 10⁻⁸ m³·kg⁻¹) was more than three times that of the original soil sample (141.1 × 10⁻⁸ m³·kg⁻¹). The magnetic substances within the strong magnetic fraction showed obvious enrichment in Cd, Cu, Pb, and Zn, with respective enrichment coefficients of 1.2, 2.2, 1.5, and 1.4, and their contents were higher than those in both the original soil sample and the weak magnetic fraction. Magnetic separation increased the contents of magnetic substances and heavy metals in the soil samples, which was more conducive to uncovering the relationship between magnetic indices and heavy metal contents. The correlation between the magnetic susceptibilities of the strong magnetic fraction and the original soil sample can indicate the degree of heavy metal pollution in urban soils, with a stronger correlation indicating more severe heavy metal pollution. Our findings demonstrate that the magnetic susceptibility of the strong magnetic fraction reflects heavy metal pollution and can thus play an important role in evaluating heavy metal pollution in urban soils.</p>