As one of the important physical properties of soil, particle size distribution (PSD) and spatial variation is of great significance not only to the transport of soil solute, water and salt, but also to soil fertility status and so on. Based on the grasslands (desert grassland, natural grassland, abandoned grassland, seasonal grassland and forbidden grassland) under the different management modes in the northern Junggar and southern Altay Mountains, the texture classification and fractal theory were used to study PSD characteristics of grasslands. The results showed that clay content in the study area was the lowest with the minimum value of only 0.17 g/kg while sand content was the highest with the maximum value of 900.37 g/kg; PSD showed a single peak, indicating that the soil is poorly developed; Silt and sand contents showed significant negative correlation with the correlation coefficient of 0.999 8 (P<0.01), suggesting that soil parent material and geographical differences lead to sand and silt particles almost accounted all of the soils. Mean clay content decreased with the increase of soil depth in desert grassland, natural grassland, and abandonment grassland, while no such tendency was found in the seasonal grassland and forbidding grazing grassland. The fractal dimension of D in desert grassland is the highest, which may be because the shrubs, as dominant plants in the ecosystem, can effectively slow down the process of reverse succession and extinction and had a certain effect in the accumulation of fine particles; Fractal dimension D had significant correlation with and clay content of all soils and with silt and sand contents of desert grassland, natural grassland, and abandonment grassland, whereas not with those of seasonal grassland and forbidding grazing grassland. The above results showed that the interference of spring and autumn grazing on soil may exceed soil bearing capacity, damage largely soil particles and hinder soil development, and the length of grazing transforming into prohibition may determine whether the development of the soil is good or not.