Abstract: 【Objective】The purpose of the study was to clarify the effects of elevated atmospheric CO₂ concentration on the stability of black soil organic carbon，and to provide theoretical basis for black soil carbon neutralization in response to climate change. 【Method】With black soil as the research object，on the basis of the open-top chamber（OTCs） experimental platform of long-term positioning simulation of climate change at Hailun Agroecological Experiment Station of the Chinese Academy of Sciences，two treatments were set in this study，which were the control treatment（CK，with a CO₂ concentration of 400 μmol/mol）and elevated CO₂ concentration treatment（eCO₂， with a CO₂ concentration of 700 μmol/mol）. ¹³C isotope tracing method was used to study the effect of elevated atmospheric CO₂ concentration on the stability of organic carbon in black soil and aggregates with different particle sizes. And correlation analysis on soil organic carbon with replacement rate and half-life period was conducted.【Result】Compared with CK，eCO₂ treatment significantly increased the content of ＞0.25 mm particle size aggregate by 11.09%（P＜0.05，the same below），significantly decreased the content of 0.25-0.053 mm particle size aggregate by 23.85%，and improved the mean weight diameter （MWD）and geometric mean diameter（GMD）of aggregates. Elevated atmospheric CO₂ concentration significantly increased the organic carbon content of ＞0.25 mm particle size aggregate by 11.61%，and the organic carbon content of 0.25-0.053 mm particle size aggregate significantly decreased by 8.72%. The organic carbon content of bulk soil and the ＜0.053 mm particle size aggregate did not change significantly（P＞0.05，the same below）. Abundance of ¹³C sequentially increased with the decrease of particle size，and the elevated CO₂ concentration significantly decreased the ¹³C abundance of bulk soil and all particle sizes. The replacement rates of the bulk soil，＞0.25 mm particle size and 0.25-0.053 mm particle size aggregates increased by 34.62%，21.60%，and 57.22%，respectively，and the half-life periods significantly decreased by 34.61%，19.63%，and 36.84%，respectively，but the replacement rate and half-life period of ＜0.053 mm particle size aggregate did not change significantly. The replacement rate was significantly and positively correlated with the organic carbon content of the bulk soil and ＞0.25 mm aggregate，and the half-life period was significantly and negatively correlated with the organic carbon content of the bulk soil and ＞0.25 mm aggregate.【Conclusion】The effects of elevated atmospheric CO₂ concentration on the organic carbon content of black soil is not significant，but it increases the structural stability and the organic carbon content of macroaggregate，accelerates the turnover of organic carbon renewal in bulk soil and macroaggregate，and is beneficial to the improvement of black soil fertility.