Soil aggregates and organic carbon distribution were studied in gravel-mulched land with different planting years. The size of soil aggregates changed with cultivation time, with larger aggregates dominating in younger fields and smaller ones in older fields. Organic carbon content increased with smaller aggregate size but decreased with longer planting time. Soil carbon sequestration ability decreased with extended planting time, especially in fields cultivated for over 15 years. This suggests a need to improve soil fertility in gravel-mulched fields with long-term cultivation.