Abstract: The purpose of the investigation of the effects of straw returning combined with chemical fertilizers on farmland soil carbon sequestration capacity and economic benefits is to improve the utilization efficiency and comprehensive benefits of straw. This study was conducted in a 7-year in-situ test field. Four treatments were used to analyze the effects of different soil layers (0-80 cm) on soil carbon storage, carbon sequestration rate and crop economic benefits under the oil-rice rotation mode in the Chaohu area. These treatments included no straw returning and no fertilization (CK), conventional Fertilization (F), Straw returning + conventional Fertilization (SF), Straw returning + 80% conventional Fertilization (SDF). We found that: (1) Straw returning combined with chemical fertilization could increase soil organic carbon storage and carbon sequestration rate in the 0-50cm soil layer. Compared with conventional fertilization (F), full straw returning + conventional fertilization (SF) and full straw returning + 80% conventional fertilization (SDF) could increase the carbon storage of rapeseed season and rice season by 1.20%~23.04% and 3.86% to 19.56%, respectively. The increase of carbon sequestration rate in rapeseed season and rice season was -0.18 times to 2.70 times and 0.26 times to 1.32 times; (2) Compared with conventional fertilization (F), the yield rate of rapeseed season treated with SF increased by 8.29%, and that of rice season increased by 11.04%, while the yield of rape treated with SDF increased by 0.94%, and the yield of rice increased by 8.34%; (3) The total output value and net income of SF treatment in both rapeseed and rice seasons were the largest. Compared with F treatment, the total output value and net income of SF increased by 8.31% and 3.34%, respectively, in the rapeseed season, and the total output value and net income of the rice season increased by 11.06% and 23.57%. In summary, the combination of straw returning and chemical fertilization has great significance for the enhancement of soil carbon sequestration capacity, soil fertility and economic benefits of rapeseed-rice rotation.