Elevated atmospheric carbon dioxide (eCO₂) concentrations are affecting soil microbial processes. Extracellular enzymes secreted by microorganisms will mediate soil biochemical reactions, thus affecting soil carbon cycling. However, it is not clear how the soil carbon degrading enzyme activity included in soil extracellular enzymes and soil carbon content change when CO₂ concentration increases. In this paper, global field experimental data (2002-2021) were collected, and the effects of elevating CO₂ concentration on enzyme activity and soil organic carbon were investigated by meta-analysis, and the relationship between enzyme activity and soil organic carbon was further studied. The results showed that: (1) the activity of cellulase and ligninase under eCO₂ treatment was increased by 12.51% and 9.88%, respectively. The organic carbon content was increased by 8.04%. (2) The change of organic carbon content was significantly positively correlated with the change of ligninase activity (P < 0.01), but not significantly correlated with the change of cellulase activity. (3) Model selection analysis showed that the experimental method had a significant impact in activity of the two enzymes, in particular the FACE experiment; Soil organic nitrogen content and mean annual precipitation had significant effects on ligninase activity enhancement. It is concluded that the activity of carbon degrading enzyme is enhanced with eCO₂. External environmental factors and experimental factors also stimulated the enhancement of enzyme activity, and the increase of organic carbon content may be related to the "enzyme locking" effect of ligninase. In conclusion, eCO₂ increased soil organic carbon content and promoted soil carbon cycle. In addition, the effects of soil nitrogen content, experimental methods, mean annual precipitation and the elevation of atmospheric carbon dioxide concentration can not be ignored.