[Objective] Microbial-mediated methane oxidation plays an important role in controlling methane emissions from paddy fields. Atmospheric CO₂ enrichment could change the potential activity, abundance, and community composition of methanotrophs in paddy rhizosphere soil, and consequently, affect their role in controlling greenhouse gas emission. Currently, there are still controversies about the effect of elevated atmospheric CO₂ concentration on methane oxidation potential and methanotrophic communities in paddy fields. Moreover, the atmospheric CO₂ concentration is a slow increase process, rather than a sharp increase to certain concentrations. However, there is still no relevant research on the effect of the slow increase of CO₂ concentration on methanotrophs. Therefore, it is necessary to study the effects and mechanism of slow increase of CO₂ concentration on methane oxidation in paddy soils.[Method] In this study, a slow increase of atmospheric CO₂ concentration (an increase of 40 μL·L^-1 per year with 4 years) (EC) was set up based on the atmospheric CO₂ concentration (AC) automatic control platform. Slurry incubation, high-throughput sequencing, and quantitative PCR on pmoA genes were used to systematically investigate the methane oxidation potential, and the abundance and community structure of methanotrophs in paddy soils under different CO₂ concentrations. This study was carried out during key growth stages (e.g. tillering, jointing, flowering and milky) of rice.[Result] Results show that the variation trend of methane oxidation potential and methanotrophic abundance was consistent, and both were increased with the elevated atmospheric CO₂ during flowering and milky stages but decreased during tillering and jointing stages. Based on the data obtained from all four growth stages, the atmospheric CO₂ enrichment enhanced the methane oxidation potential by 11.7% and increased the abundance of methanotrophs by 53%. Further, the community structure of methanotrophs in soil was changed significantly, with the dominant methanotrophs shifting from type II under AC to type I under EC. There was no single environmental factor that was found to have a significant impact on methane oxidation potential, pmoA gene abundance or diversity. Also, the content of soil inorganic nitrogen (NH₄⁺-N, NO₂^--N and NO₃^--N) was decreased under EC compared with the control. The relatively lower inorganic nitrogen content in paddy soils under EC could alleviate the inhibition of nitrogen on methane oxidation in the paddy field. By stimulating the growth of rice roots and increasing soil carbon input, elevated atmospheric CO₂ can indirectly enhance the production of methane in soils, which in turn increased the methane oxidation potential and abundance of pmoA genes. The increase of rice root exudates and aerenchyma volume under EC might provide a more suitable living environment for type I methanotrophs.[Conclusion] Elevated atmospheric CO₂ promotes the growth of crops, which can subsequently increase both CH₄ and O₂ concentrations in paddy rhizosphere soil, and decrease soil nitrogen level. The combined effects of the above environmental factors could affect the methane oxidation potential, methanotrophic abundance and community structure in our paddy soils. Taken together, our results indicate a positive response of methane oxidation to the slow increase of atmospheric CO₂ concentration in paddy ecosystems, which could help alleviate global warming.