In recent decades, global warming under rising CO ₂ significantly influences external organic carbon (EOC) input and drying-rewetting processes in terrestrial ecosystems. However, little is known about how soil CO ₂ emissions respond to these perturbations, which provides us with a chance to explore potential factors and variability. In this study, a meta-analysis on the responses of CO ₂ emissions with or without EOC input in the soil drying-rewetting cycles (DWC) based on 291 observations (included 33 study sites and 11 variables) has been conducted. The results indicated that i) CO ₂ emission with the increase of EOC by 284% relative to without EOC under DWC; ii) The effect size of CO ₂ emission was the smallest in the forest (+15%) and the largest in the grassland (+1468%); iii) The CO ₂ emission effect sizes were substantially greater in complex substrates (+288%) than in simple substrates (+132%), and iv) longer drought period in a DWC can induce more CO ₂ emission. The study suggests that terrestrial CO ₂ emission may be multi folds in the long drought-rapid rewetting processes under large input of EOC.