【Objective】Based on a 36-year fertilization experiment in a field of fluvo-aquic soil, effects of fertilization, especially application of organic manure, on organic carbon fractions in the plow layer were studied in an attempt to learn comprehensively how soil carbon changes and explore effects of fertilization on the status of soil organic carbon through analysis and evaluation of soil organic carbon fractions, so as to better master the physico-chemical and biological mechanisms of the changes in soil organic carbon fractions as affected by long-term fertilization and to provide scientific basis for decision-making for fertilization in sustainable development of agriculture. 【Method】 In this study, physical means were used in combination with chemical ones to determine contents of organic carbon, easily oxidized organic carbon, particulate organic carbon and mineral incorporated organic carbon in soils, and effects of fertilization on soil organic carbon fractions were analyzed. To that end the experiment in the study was designed to have 8 treatments, that is, no fertilization (CK), application of N alone (N), application of N and P (NP), application of N, P and K (NPK), application of organic manure (M), application of nitrogen fertilizer plus organic manure (MN), application of nitrogen and phosphorus fertilizers plus organic manure (MNP), and application of nitrogen, phosphorus and potassium fertilizers plus organic manure (MNPK). 【Result】Results show that long-term fertilization significantly improved soil fertility. Application of organic manure was closely related to increase in soil organic carbon, particulate organic carbon and mineral incorporated organic carbon. Fertilization significantly increased the content of easily oxidized organic carbon (EOC) in the soil. The effect was the most significant in Treatment MNPK with an increase up to 72.13% as compared with CK, while EOC content in Treatment MN, MNP and MNPK increased by 23.18%, 12.53% and 25.92%, respectively, as compared with their respective chemical counterparts, Treatment N, NP and NPK. Fertilization (except for N application alone) significantly increased the content of soil particulate organic carbon (POC). The effect was particularly significant in organic manure-amended treatments, whose mean POC content was 92.69% higher than that of the treatments without organic manure. The content of mineral incorporated organic carbon (MOC) in the organic manure amended treatments was 10.06% higher than that in CK,. The proportion of particulate organic carbon (POC/SOC) in Treatment MNPK increased by 13.33%, while the proportion of mineral incorporated organic carbon (MOC/SOC) decreased correspondingly, as compared with those in CK. Application of organic manure significantly enhanced the contribution of increased total organic carbon to MOC, especially Treatment MNPK where the increased total organic carbon and the native total organic carbon formed a ratio of 1:1 in POC and MOC. 【Conclusion】In conclusion, application of organic manure, especially when in combination with balanced nitrogen, phosphorus and potassium fertilizers, is of great significance to improving soil physico-chemical properties, expanding the fractions of organic carbon, and promoting balanced distribution of newly-sequestrated carbon in various carbon fractions. The findings in the study may serve as a theoretical basis for rational fertilization in sandy loam fluvo-aquic soils.