A long-term filed experiment was conducted to investigate the influence of ridge-cultivation and no tillage on distribution of soil organic carbon (SOC) in soil profiles of paddy fields located in Southwest China, and determine SOC accumulation characteristics in paddy soil profiles under long-term ridge-cultivation and no tillage. The experiment included four cultivation treatments: conventional tillage with rotation of rice and winter fallow (CT1), conventional tillage with rotation of rice and rape (CT2),ridge-cultivation and no tillage with rotation of rice and winter fallow (NT1), ridge-cultivation and no tillage with rotation of rice and rape (NT2). After the field experiment were conducted for 20 years, the highest and lowest SOC concentrations in different soil layers (0-10 cm, 10-20 cm, 20-40 cm and 40-60 cm) were found in treatments NT2 and CT2, respectively. SOC concentrations in the 0-10 cm and 40-60cm layers had no significantly difference among treatments NT1, NT2 and CT1, and SOC concentration in the 20-40 cm layer was significantly higher in treatment NT2 compared to other treatments (P NT1 > CT1 > CT2, and there was significantly difference among all the treatments (P<0.05). In conclusion, compared to other treatments, treatment NT2 result in more organic carbon accumulated in the 20-40 cm layer, and is a more effective option for SOC sequestration in paddy field.