Abstract：[Objective] To analyze the response of soil aggregate grain size composition and stability and the organic carbon content of all levels of aggregates to the simulated warming, and to provide a scientific basis for the dynamic change of soil structure stability and carbon storage capacity of the oil pine plantation forest in Daqingshan, Inner Mongolia, in the context of climate warming. [Methods] The 0~40 cm soil of the oil pine plantation forest in Daqingshan, Inner Mongolia, was used as the study object, based on a 4a year-round simulated field warming experiment, the soil was divided into three grain sizes of >0.25 mm, 0.25~0.053 mm and <0.053 mm by wet sieving method, and the organic carbon content in the agglomerates of each grain size was measured. [Results] (1)The soils in this study area have microaggregate as the dominant grain size, and warming decreased the soil macroaggregate content and microaggregate content in all soil horizons, whereas the powdered clayey aggregate content showed a significant increase in all soil horizons, by 14.92%, 14.01%, and 13.84%, respectively; (2) Compared to the control, both soil mean weight diameter (MWD) and geometric mean diameter (GMD) were significantly reduced by warming, with MWD decreasing by 5.93%, 3.66%, and 5.68%, respectively, and GMD decreasing by 8.83%, 8.41%, and 10.63%, respectively, in all soil horizons; (3) In both treatments, the highest organic carbon content was found in soil powder and clay particles, and the warming increased the organic carbon content in powder and clay agglomerates but decreased that in macro- and micro-agglomerates; the total organic carbon content of the surface soil increased after the warming, while the organic carbon content of the soil layers from 10~20 cm and from 20~40 cm decreased; (4) The organic carbon contribution of soil powdery clay aggregates was the largest under warming conditions; compared with the control, the organic carbon contribution of soil powdery clay aggregates increased by 44.39%, 39.60%, and 43.31% in each soil stratum after warming; followed by micro-aggregates, and soil macro-aggregates had the lowest organic carbon contribution. [Conclusions] It was found that warming led to changes in soil aggregate composition, destabilized soil aggregates, and reduced organic carbon content in macro- and micro-aggregates, suggesting that warming is not conducive to the physical conservation of soil organic carbon.