Abstract: The particle size distribution could have impact on water movement in soil and solute migration as well as water loss and soil erosion. In order to study the distribution characteristics of soil particle size in the vertical direction, water sieve analysis and laser particle size analysis of soil particle size of rare earth ore in Jiangwozi in Gan county, Jiangxi were conducted. The result shows that the distribution of particle size is affected by weathering degree and vertical migration of particles. The distribution is as follows: (1)According to its diameter, soil particles can be divided into coarse, fine, powder, clay structure and the coarse particles of the soil are mainly quartz, in addition, the distribution of soil particles in the rare earth mine can be characterized as hump type. The contents of particle size in the coarse particles ( > 2mm) and clay ( < 0.075mm) are high, while the content of the particle size in fine powder (0.075-2mm) is relatively low.(2) Because of the influence of weathering degree and vertical migration of particles, the content of fine and clay granules in the rare earth mineral increases first and then decreases in tracing pattern.(3) Laser particle size analysis of clay ( < 0.075) shows that particle size distribution changes with the size of the particle size which is similar to the distribution in depth of particles whose size is greater than 0.075 millimeter.