In order to explore effect of long time rice-cultivation on soil organic carbon (SOC)dynamics in soil profile, SOC dynamics was investigated in profiles of paddy soils along a rice-cultivation chronosequence.The rice (Oryza sativa) cultivation chronosequence included 50,100, 500, 700, 1000 and 2000 years.After 50 years of rice cultivation, SOC contents in topsoil of paddy soils were stable and less influenced by cultivation periods.SOC contents below about 40 cm depth for older paddy soils were higher when compared to paddy soils cultivated for 50-500 years.VR indicated the variation range (%) of the SOC density between the 0-40 cm and 40-80 cm layer.VR values of paddy fields throughout the chronosequence decreased with increasing rice-cultivation periods.The δ13C value in profiles of paddy soils increased gradually with soil depth.Across the chronosequence, the δ13C difference between the bottom layers and topsoil decreased with cultivation periods.Below about 60 cm soil depth, the δ13C difference between SOC and the rice-derived residue also decreased with cultivation periods.C/N ratios of SOC in subsoil of older paddy soils had higher values when compared to younger paddy soils (50-500 years).The Change of SOC density, δ13C values and C/N ratios in soil profiles fully indicated long-term rice cultivation with irrigation could induce that young and low δ13C rice-derived organic carbon was accumulated and sequestrated in subsoil.Therefore, more and more young organic carbon was sequestrated in subsoil with the increase of rice-cultivation periods.The findings supported that paddy soils cultivated for hundreds to thousands of years were still a potential C sequestrator, and functioned as a carbon sink of atmospheric CO2.