Abstract: A study has been undertaken in experimental field sat Southwest University in Beibei, Chongqing, in order to explore changes in soil aggregate distribution and organic carbon content, and to estimate soil carbon sequestration potential, in southwest China farmland that uses the triple cropping system (wheat/corn/soybean). There were two treatments: traditional tillage (T) and T plus straw mulching (TS). There was a significantly negative correlation between >2 mm and 2-0.25 mm aggregate contents (r=0.985, P<0.05) during the planting periods of the three crops. The responses of soil aggregates to the different crops varied. In the wheat and soybean belts, the content of water-stable aggregates (>0.25 mm) was as high as 90% of total soil, while it was approximately 80% in the corn belt, indicating that corn performance was beneficial to the formation of soil water-stable micro-aggregates. Straw mulching significantly increased soil organic carbon content and particle size at the 0-5 cm and 5-10 cm soil layers. Increases in organic carbon content at the 5-10 cm soil layer were especially notable. Soil carbon sequestration potential was greater in the corn than in the wheat and soybean belts. The study shows that the distribution of soil aggregates and of organic carbon content in soil particles with different sizes were influenced by both tillage measures and crops. In conclusion, the selection of crops and straw mulching will play important roles in promoting soil carbon sequestration in the dryland, triple cropping systems of southwest China.