The distribution characteristics of topsoil particle size can reflect the regional characteristics of the district environment，research on the internal topsoil particle size distribution of small watershed in wind water erosion region could provide a theoretical basis for exploring the mechanism of water and soil erosion. By field sampling and laboratory determination of surface space，study on surface soil particle size distribution characteristics and wind-erosion possibilities of Dong Liu Gou basin which located in the area of wind-water erosion. The results were as follows：soil particle size of Dong Liu Gou watershed was mainly concentrated in the fine sand (50～250μm)，volume fraction between 56.59%～86.65%，belonging to aeolian sandy soil .There was a significant difference between the state of the size among different land use types. The Mz of grassland，farmland and shrub were 77.60μm，81.66μm and 87.85μm respectively，in which the particle size distribution was small. While the Mz of sandy land and river channel was large，which were 126.36μm and 151.80μm respectively in/with coarse particle size. Most of the topsoil particle size showed a positive bias and narrow peaks，particle distribution is more concentrated. The rough phenomenon of the topsoil grain size has been shown obvious from upstream to middle reaches，specific performances：the Mz of the land use in the upper reaches was smaller than that in the middle and lower reaches except the river channel(p＜0.05). While in the middle reaches，there was not significant difference between sandy soil and other land types in Mz except the grassland and river channel. After analysis the possibility of wind erosion of the topsoil in the watershed，we found that the erodible particles content significantly increased from upstream to the middle reaches，which were increased by 44.4%，54.23%，48.84%，33.76% in grassland，cropland，shrub，river，respectively. The conclusion showed that the middle reaches was the region where the topsoil particle size distribution was most complex and the wind erosion was most intense，and also and also the major area where wind and water erosion interacted.