Benggang erosion is a large-scale, rapidly developing phenomenon that commonly occurs in the granite hilly region of southern China and severely endangers local land resources and the ecological environment. A developing Benggang in southeast China was selected to explore the non-uniformity of soil particle size distribution (PSD) and the nutrient heterogeneity during Benggang erosion using multifractal theory. The results showed significant differences in the soil particle composition and nutrient components of different parts of Benggang. The generalized dimension spectra exhibited an inverse “S” decreasing pattern and the singularity spectra showed a left hook shape, indicating that the soil PSD of Benggang features high non-uniformity and can be described by the multifractal theory. The information dimension (D1) and the correlation dimension (D2) were high in the uppercatchment, the lowerportion ofthe collapsingwall, and the top ofthe alluvialfan. D1, D2, and the spectral width (Δα) were negatively correlated with clay and silt content but positively correlated with sand content. In contrast, D1–D2 and the degree of symmetry (Δf) showed opposite relationships. The multifractal singularity indexes α0 and Δα were significantly negatively correlated with soil organic matter but positively correlated with bulk density; opposite correlations were observed for Δf. The findings revealed that the multifractal theory can quantitatively characterize the characteristics of soil PSD and laterally reflect soil nutrient loss. This research introduces a scientific method for quantitatively describing the heterogeneity of soil PSD during Benggang development. In addition, it also provides a theoretical basis for controlling Benggang erosion to protect the environment of the southern granite region.