The effect of soil physical and chemical properties, soil aggregate and its characteristics of planting ramie and peanuts in red soil were studied by dry, wet sieving method. Moreover, the relationship between soil aggregates and surface runoff and soil erosion were also analyzed. The results indicated that: (1) After three years by planting ramie, soil organic matter, field capacity, total porosity, grains of sand were increased 28.44%, 10.06%, 5.65%, 28.44%, soil bulk density, silt, and clay were reduced by 7.20%, 14.85%, 34.95%(p<0.05); (2) Mean weight diameter(MWD), stability index(ASI) of soil aggregate by planting ramie were significantly higher than that of planting peanut, soil aggregate stability of planting ramie was better than that of peanuts; (3) 0.25~1 mm aggregates is the best chance of preservation of the red soil, and the resist-erosion ability also the strongest. (4) Surface runoff and soil erosion, with soil organic matter, sand content, >1 mm dry aggregates, >0.5 mm water stable aggregates, MWD, ASI were negatively correlated(p<0.01), but were significantly positively correlated with silt, clay content, <0.25 mm,dry aggregates, and <0.053 mm water stable aggregates.