Abstract: Spartina alterniflora has strong carbon sequestration. Understanding the methane fluxes of S. alterniflora communities can provide important parameters for assessing the net carbon sink function of S. alterniflora. This paper systematically summarizes the general characteristics and mechanism of CH₄ emission by S. alterniflora communities in coastal wetlands of China. Results show that (1) CH₄ flux in different regions shows no obvious patterns and differed significantly. Environmental factors in different environments have a comprehensive regulatory effect on CH₄ emission, and most of them affect CH₄ flux by affecting microorganisms related to CH₄ production in soil. (2) CH₄ flux is the highest in summer and lower in winter and spring. The diurnal flux is in irregular fluctuation, but the total daytime flux is higher than that at night. The seasonal difference of CH₄ flux is positively correlated with temperature, biomass and light. Temperature affects the activity of microorganisms involved in CH₄ production. Biomass provides organic matter for CH₄ production, while light affects the synthesis of organic matter through photosynthesis. In addition to temperature and light, the diurnal difference is mainly affected by tidal changes. (3) The CH₄ flux without water flooding is much greater than that with water flooding. In the tide stage, the lower part of S. alterniflora is blocked as an important channel for CH₄ emission to the atmosphere. At the same time, CH₄ is stored in the soil or discharged into the tide, and then to the atmosphere after ebbing tide. Therefore, the CH₄ flux is lower during flooding. (4) Mowing would reduce CH₄ flux. S. alterniflora provides an important raw material for CH₄ production, and simultaneously uses aerenchyma to release CH₄ into the atmosphere. Mowing cuts off the CH₄ transmission path and reduces the aboveground biomass and thus the CH₄ flux.