Abstract: Abstract: Reclaimed soil particle size distribution (PSD) is different from the normal soil, one main reason is that the soil are compacted by machineries in the process of reclamation, and PSD is closely related to the ability to protect water and fertilizer of soil , so the changing mechanism of PSD caused by the large machinery for reclamation construction is a noteworthy matter. In this research, we established a study area on a filling reclamation site in mining area with high ground-water table in order to study the effects of mechanical compaction to reclaimed soil PSD. Aimed to have a better description of the whole reclamation process, we set up different number of compaction times (0, 1, 3, 5, 7, 9), and divided the reclaimed soil into three layers based on its construction, two backfilling surface soil layers (0-20, 20-40 cm) and one packing soil layer (40-60 cm). Before compacted by the machinery, the surface soil (0-40 cm) was sandy loam, soil density was 1.321 g/cm3, soil volumetric water content was 22.9% at available water content, and 50 kPa was added for each compaction. The reclamation site was divided into 31 plots, and we collecting 13 soil samples on the same plot in order to avoid the variation of soil characteristics. In this research, we used the LS13320 laser particle size analyzer test soil PSD after using hydrogen peroxide and hydrochloric acid to remove organic matter and carbonate from soil respectively, and adopted multifractal method that could describe the heterogeneity of the soil to quantify the reclaimed soil PSD characteristics. The results showed that: mechanical compaction evidently affected soil PSD of topsoil (0-20 cm) and subsoil (20-40 cm), the size of soil particles were refined with the increasing of compaction times, and the peak of soil particle distributions moved from clay range to sandy randy. Reclaimed soil PSD had a multifractal feature, the generalized dimension spectra q-D(q) curve was a "S" decreasing function and soil particles were distributed in concentrated areas. The singular spectra α-f(α) was a convex curve with left hook and the large probability subset of soil particles was a dominant position. Under the compaction of machinery, reclaimed soil particles encountered the varying local stacking degrees, especially those distributed in sparse areas. Machinery compaction significantly affected the PSD heterogeneous characteristics of topsoil (0-20 cm) and subsoil (20-40 cm), with the increasing of compaction times. Volume dimension D (0) decreased, representing the range of PSD was reduced, singularity spectra symmetry degree Δf increased, representing the symmetry of PSD was added, and information dimension D (1). Information dimension/volume dimension D(1)/D(0), correlation dimension D (2) and singularity spectra width Δα had fluctuating change, representing the concentration, uniformity and local intensive degree of PSD had fluctuating change. The research found that D(1) and D(1)/D(0), D(2) and Δα had similar actions on representing the concentration and uniformity of PSD respectively, and the correlation coefficients were 0.767(P<0.01) and-0.488(P<0.05), multifractal parameters could be used to describe the subtle changes of PSD in the process of mechanical compaction, and reclaimed soil compactness had very significant correlations with D(0), Δα and Δf, with the correlation coefficients of -0.840, -0.755 and 0.782(P<0.01), respectively, showing that the greater compactness reduced the range of PSD, and added its non-uniformity and symmetry, and D(0), Δα and Δf were sensitive to the change of reclaimed soil compactness. This provided an accurate analysis method for further research on mechanical compaction of reclaimed soil.