[Objective] Increases in atmospheric CO₂ concentration have certain direct or indirect impacts on CH₄ emission from rice paddy fields. So it is of great significance to have an in-depth study on impacts of long-term elevated atmospheric CO₂ concentration on CH₄ emission and related microorganisms for assessing and managing CH₄ emissions from rice paddy fields in the context of future climate.[Method] To investigate effects of long-term elevated atmospheric CO₂ concentration on CH₄ emission and its mechanism, CH₄ emission fluxes and abundance of the methanogens and methanotrophs under ambient CO₂ (ACO₂) and elevated CO₂ conditions (ECO₂) in rice paddy fields were monitored during the 2016-2017 season, with the aid of the Chinese rice FACE platform that has been operating for more than 10 years. Moreover, meta-analysis was conducted to determine quantitatively effects of elevated CO₂ relative to duration on CH₄ emission from and the abundances of methanogens and methanotrophs in rice paddy fields.[Result] Results show that compared with ACO₂, long-term ECO₂ significantly reduced CH₄ emission and the abundance of methanogens by 28% and 39%, respectively (P<0.05), but increased the abundance of methanotrophs by 21% (P>0.05). Meta-analysis shows that with the increase in duration of CO₂ elevation, the effect of elevated atmospheric CO₂ concentration promoting CH₄ emission and the abundance of methanogens gradually decreased, while the effect on the abundance of methanotrophs gradually increased.[Conclusion] Therefore, it could be concluded that under future climate conditions, long-term elevated CO₂ will reduce CH₄ emission from rice fields, which is of great significance for mitigating the greenhouse effect brought about by rice cultivation.