Abstract: This study aims to present the influence of water erosion on the soil structure and distribution of organic carbon in a special terrain. The samples were collected in a small watershed of Qingyuan Mountain, a typical hilly area of red soil in southern China. The nuclide 137Cs tracer technology was used to analyze the water and soil loss during the gully erosion in the small watershed. An attempt was also made on the influence of soil erosion on the stability of soil aggregates and the content of organic carbon in the gully erosion area. Three soil depths (0-10, >10-20, >20-30 cm) were set to identify soil aggregates, and the scouring features of soil aggregates and organic carbon. The whole soil samples were gathered at the depth of 0-20 cm by the soil auger in the diameter of 5 cm, where the interval of 5 cm from different soil layers was used to determine the content of soil nuclide. A gamma spectrometer was used to measure the 137Cs content, and further to calculate the area specific activity. A wet sieving was utilized to obtain the aggregates with four particle sizes (>2 mm, 2-0.25 mm, 0.25-0.053 mm and <0.053 mm). The approach of heating on a potassium acid water-bath was adopted to obtain the content of organic carbon in the aggregates. One-Way ANOVA, Duncan significance test and redundancy analysis operations were used to examine the correlation between content of soil aggregate organic carbon and physical and chemical properties. The results found that the top layer of gully erosion had the highest 137Cs content, even higher than the background value, indicating the sedimentary area, whereas, the upper slope and the lope toe were moderately eroded, while the slope mildly was eroded. The evolution of gully erosion area successively went through the absolute deposition, absolute erosion, relative deposition, absolute erosion in a top-down way along the slope, in which the vegetation and terrain were the dominant factors. The content of large aggregates in the sedimentary area was significantly higher than that in the eroded area, whereas, the eroded area had significantly higher content of microaggregates, whose components continued to increase as the erosion intensity strengthened. Moreover, the soil aggregates in the sedimentary area had a higher stability, whereas, the lowest stability occurred at the mostly eroded toe of slope. Compared with the upper and toe slope, the soil aggregates in the middle slope of erosion area showed higher values of macroaggreages content and mean weight diameter. The content of organic carbon in soil aggregates for all particle sizes was higher in the sedimentary area than that in the erosion area. There was also uniform distribution of organic carbon in soil aggregates in the erosion area. The content of organic carbon in the large aggregates was significantly higher than that in the microaggregates. The correlation analysis results showed that the organic carbon of only 2-0.25 mm aggregate contributed positively to aggregate stability (P<0.05), and the correlation coefficient was 0.75. It infers that the content of organic carbon in the microaggregates was positively correlated with the increase of erosion intensity. Compared with traditional slopes, the top of gully erosion area was a depositional site, but other slopes were erosional sites. The soil structure and related carbon components were mainly affected by the degree of soil erosion under the domination of terrain and vegetation. Therefore, the specific measures of water and soil conservation if appropriate can be taken in special terrains in red soil areas of southern China.