Abstract: In order to study the effects of Salix psammophila sand barrier on soil particle size distribution (PSD) and soil organic carbon (SOC), multi-fractal features of soil PSD and SOC of a mobile sand dune, a fixed sand dune of a two-year sand barrier and a semi-fixed sand dune of a seven-year sand barrier were analyzed in Maowusu Sandy Land with the multi-fractal method. The results showed that the silt, clay and very fine sand contents of setting sand barrier dunes increased, while those of the fine sand and medium coarse sand decreased. The heterogeneity and width of soil PSD could be reflected by the multi-fractal parameters such as D₁/D₀ (i.e., information dimension/capacity dimension) and -f() (i.e., multi-fractal spectrum). The ratios of D₁/D₀ of the fixed dune and semi-fixed dune were higher than that of the mobile dune, and the decreasing order of D₀ was:sand dune with seven-year sand barrier (1.01) > mobile sand dune (1.00) > sand dune with two-year sand barrier (0.93). The order of D₁ was mobile sand dune (0.91) > sand dune with two-year sand barrier (0.88) > sand dune with seven-year sand barrier (0.65). The multi-fractal parameters were obviously related with the soil clay content. The soil plasma content increased when the soil heterogeneity was large. There was an obvious decreasing trend in SOC content of the three different types of dunes. There was a strong correlation between the SOC content and D₁/D₀ of PSD. Therefore, the multi-fractal soil parameters can be used as an indicator to reflect the concentration of soil nutrients. There was an obvious increasing trend of SOC content for the three different types of dunes with the setting years, and the SOC content of the seven-year sand barrier was significantly different from the other two sand dunes. Additionally, there was a significant correlation between the SOC content and the multi-fractal parameters of PSD. Therefore, the multi-fractal parameters can be used to interpret the change of soil nutrient status.