This study investigated the characteristics of heterogeneity and non-uniformity of soil particle size distribution in semi-arid grasslands after grazing exclusion, to evaluate the influence of grazing exclusion on the distribution of soil particle size of grassland. Our results are expected to provide support for the rational restoration and management of degraded grasslands. We examined the changes in soil particle size distribution using the multi-fractal theory at different layers (0—10 cm, 10—20 cm, 20—40 cm, 40—60 cm) along a 35-year chronosequence following grazing exclusion of grassland in Yunwu Mountain, Ningxia autonomous region, and revealed the dominant drivers for the variation of soil particle size. The results showed that grazing exclusion resulted in a reduction of soil bulk density, while an increase in underground biomass, soil nutrients contents such as organic carbon, total nitrogen, and water content, and these values peaked at 27 years after exclusion. Changes of multifractal spectral functions (Δf > 0) showed that the soil was dominated by particles with larger size, and the sand content accounted for 69.29% of total particles at the late period of exclusion (35 years), which was significantly higher than that in the early period (10 years). The capacity dimension (D₀) increased with the exclusion years, ranging from 0.866 to 0.891, The information entropy dimension (D₁) and the correlation dimension (D₂) showed a trend of first increasing and then decreasing, and increased with the soil depth at the 10-year and 15-year sites, while decreased with the soil depth at the 35-year site. D₁/D₀ decreased with soil depth, ranging from 1.012 to 0.904. There was a significant positive correlation between soil particle size distribution and soil organic carbon, indicating that soil organic carbon was the main factor affecting the particle size distribution. Our results indicated that 27-year exclusion could improve the soil nutrient levels and soil structure status, but a long-term exclusion was not conducive to the restoration of degraded grassland in the semi-arid region.