Spatial distribution of soil organic carbon (SOC) is one of the key issues of the study on SOC sequestration, and plays a crucial role in understanding SOC storage dynamics. A research project on distribution of SOC in soil aggregates, profile, and field of purple paddy soil that is widely distributed in the Sichuan basin, was initiated in 1990.Results show that the highest organic carbon content in aggregates was discovered in the fraction of 2～0.25 mm in particle size, while total organic carbon (TOC) in aggregates was mainly distributed in the fractions of 0.25～0.02 mm and 0.02～0.002 mm. The content of SOC in aggregates trended to be greater (enrichment coefficient, EC > 1.5) in macroaggregates (> 0.25 mm) at depth of 0～10 cm under non-tillage ridge culture. In conventional fields under flat culture, paddy-upland rotation and ridge culture, SOC concentration decreased slowly with the increase in depth. Organic carbon content was significantly (p< 0.05) different between treatments. Distribution of soil organic carbon and some related properties of the topsoil layer of the experiment field demonstrated significant spatial variation, forming stripes and patches. The treatment of non-tillage ridge culture was the highest in SOC content, reaching 30.71 g kg^-1, while the treatment of conventional flat culture the lowest being only around 16.50 g kg^-1. Longterm non-tillage ridge culture may lead to enrichment of SOC in macroaggregates of the surface soil layer and differentiation between layers of the soil profile.