The particle-size characteristic of eroded sediments is important in understanding, characterizing and modeling the transport behavior of sediment and sediment-associated chemicals. The objective of this study was to provide references through summary and reorganization of relevant researches at home and abroad. This paper reviewed and evaluated the transport forms of eroded sediments, the primary particle-size composition of sediments undispersed with different size, the enrichment and selectivity of different size-class particles, and factors. Some results reached a consensus:(1) Undispersed sediment-size distribution is required for describing and modeling sediment transport and the associated movement of nutrients and contaminants. (2) This erosion selectivity, in fact, primarily results from the energy limitation of rainfall and runoff. When the energy is small, runoff is preferred to transport fine particles, and sediment is mainly enriched by fine particles. As the energy gradually increases, the sediments gradually thicken. When the energy is large enough to produce rill, the sediments size distribution tends to be close to the original soil. (3) The size distribution of sediments for the well-aggregated soils usually is much coarser than the less-aggregated one.