Based on the CH₄ flux data of rice-wheat rotation farmland observed by eddy covariance method from November 2019 to October 2020 in Shouxian County， Anhui Province， this paper analyzed the CH₄ flux characteristics of rice-wheat rotation farmland and its short-term response process to rainfall. Results show that the rice-wheat rotation field in Shouxian was the source of CH₄， and the annual CH₄ flux was about 20.52 g·m^-2. The rice growth stage was about 15.71 g·m^-2， accounting for 77.6% of the annual CH₄ flux， and the maximum was at tillering stage (11.63 g·m^-2). The CH₄ flux of winter wheat growth period was about 1.20 g·m^-2， and of which the jointing period (0.66 g·m^-2) was the largest. The fallow period was about 3.60 g·m^-2. The diurnal variation of CH₄ flux of winter wheat showed a single-peak type， and the peak appeared mostly in the afternoon， while the diurnal variation of CH₄ flux of the rice showed both double-peak and single-peak types. The effect of rainfall on the peak time of CH₄ flux had a time lag， and the delayed effect of heavy rain in rice growth stage was the most obvious. CH₄ flux was significantly correlated with rainfall. Light rain during the rice growth period increased the CH₄ emission capacity， but there were no significant differences in different levels of rainfall and rainfall intensity， respectively. However， moderate rain and heavy rain during winter wheat growth period both enhanced the CH₄ emission， and the farmland was prone from a CH₄ sink to a CH₄ source with the increase of rainfall intensity.