In order to investigate the effects of saltwater intrusion due to sea level rise in the context of global climate change and the transport of large amounts of Fe by rivers under heavy rainfall conditions on CO₂emissions from estuary wetland ecosystems, the Daoqingzhou freshwater wetland of Cyperus malaccensis in the estuary of the Min River was selected as a study object, a mesocosm simulation experiment was conducted, combined with gas chromatography, to study the effect of saltwater-coupled Fe(III) input on CO₂ emissions during the growing period of plants in the estuary wetland. The results showed that: 1) Saltwater input, Fe(III) input, and saltwater coupled with Fe(III) input significantly contributed to CO₂ emissions fluxes in estuary wetland ecosystems (P<0.05), but there were no significant differences among the three treatments. 2) Saltwater input, Fe(III) input, and saltwater coupled with Fe(III) input significantly reduced the temperature sensitivity of soil CO₂ emissions in estuary wetlands (P<0.05). 3) Soil β-glucosidase (βG) and cellulose hydrolase (CBH) activities were lower, and β-N-Acetylglucosaminidase (NAG) and acid phosphatase (AP) activities were higher; saltwater input, Fe(III) input, and saltwater coupled with Fe(III) input significantly inhibited soil βG activity (P<0.05). 4) The emission flux of CO₂ from the estuary wetland was significantly positively correlated with soil conductivity, and significantly negatively correlated with soil temperature, soil βG and CBH activities (P<0.05). In conclusion, saltwater input, Fe(III) input and saltwater-coupled Fe(III) input all promoted CO₂ emissions during the growing period of plants in estuary wetlands, but there were no significant differences among the three treatments, indicating that the effects of two factors input on CO₂ emissions were not a simple superposition of single-factor input because of an interaction between the two factors in estuary wetland ecosystems. Meanwhile, the saltwater-coupled Fe(III) input aggravated the environmental stress under high-temperature condition, and thus inhibited microbial activity and reduced the sensitivity of CO₂ emissions to temperature in the wetland ecosystem of the Min River estuary.