The land use types and environmental factors have a great significance on soil particle size distribution (PSD). However the effects are different in different scales. Research on the relationship between topsoil particle size distribution and land use & environmental factors can provide a basis for assessing topsoil physical properties in loess hilly-gully area. The study was conducted in the Muyu small watershed and the Ansai catchment in the loess hilly area of the Loess Plateau in China, and the comparative analysis of soil particle size distribution and its influence factors in different scales were carried out. The research results showed that: (1) The topsoil in the loess hilly-gully areas of the Loess Plateau are mainly composed of sand and silt in both small watershed and catchment. The percentage of each particle size is medium spatial variability, and the spatial variability of D is far below of the particle size. But it appears clearly that the spatial variabilities are scale dependent and it increases with the increase of study area. (2)The effects of land use types on soil particle size are different at two scales. The sand content varied with land use in the order: grassland> farmland> woodland> shrub land> orchard land in the Muyu small watershed, and grassland> shrub land> woodland> orchard land> farmland in the Ansai catchment. The silt content varied with land use in the opposite order of the sand content. The D value varied with land use in the order: shrub land> grassland>woodland> orchard land> farmland in the Muyu small watershed, and shrub land>grassland>farmland>woodland>orchard land in the Ansai catchment. (3) In both Muyu small watershed and the Ansai catchment, D is very significant positive correlation with the soil sand content and clay content, significant negative correlation with soil silt content, and D value is much higher in the sandy loam than that in the loam and silt loam. (4) Vegetation cover, altitude and position have more influence on the soil particle size than other factors in the Muyu small watershed, while vegetation cover, land use, and slope influence the soil particle much more greatly in the Ansai catchment.