Soil organic carbon is the crucial driver and regulator of the agricultural ecosystem. In particular, the quantification of rhizosphere organic carbon plays an important role in the soil carbon cycle and mineral nutrient release. Through the research on the changes of organic carbon, labile organic carbon and organic carbon structure in soybean rhizosphere soil under different long-term fertilization, we can further understand the mechanism of rhizosphere organic carbon fixation and stability. The outcome of this research would provide a scientific basis and theoretical support for improving carbon fixation of farmland ecosystem and sustainable development of farmland. The experiment uses a　long-term　black　soil　positioning test. Chemical analysis and 13C-NMR were used to study dynamic changes in organic carbon, labile organic carbon and organic carbon structure in soybean rhizosphere soil. The results showed that organic carbon concentrations were generally higher in rhizosphere soil than in bulk soil. Long-term fertilization treatment could significantly increase concentrations of organic carbon and low labile organic carbon in rhizosphere soil, and MNPK treatment had the best effect. Compared with CK treatment, MNPK treatment significantly increased the proportion of alkyl C, O-alkyl C and the ratios of alkyl C to O-alkyl C, and decreased aromatic C and the ratios of aromatic C to total C in rhizosphere soil, especially in bulk soil.NPK treatment increased the proportion of aromatic C and the ratios of aromatic C to total C, increased alkyl C and the ratios of alkyl C to O-alkyl C in rhizosphere soil, and decreased O-alkyl C, which the results were opposite in bulk soil. The above analysis showed that: MNPK treatment significantly increased the content of rhizosphere organic carbon, increased alkyl C, O-alkyl C and the ratios of alkyl C to O-alkyl C while promoting the formation of aggregates and increased the stability of soil particle structure. NPK treatment increased aromatic C, and the ratios of aromatic C to total C reduced the rhizosphere O-alkyl C, which decreased the stability of aggregates. At the same time, it is proved that 13C-NMR technology combined with semi-quantitative analysis could be used to comprehensively analyze the structural changes of different organic carbon functional groups to gain a deeper understanding of the stability mechanism of rhizosphere soil organic carbon.