Abstract: Salinity has a profound influence on methane(CH₄) production and emission in estuarine wetlands.In order to reveal the effects of seawater intrusion on CH₄ emission from estuarine wetlands, static closed chamber combined with a gas chromatograph technique was used to investigate the flux of CH₄ at a Phragmites australis wetland in Chongming Dongtan from april to october in 2016.The results showed that the flux of CH₄ was higher in spring and summer than in autumn and winter.The flux ranged from 0.19 to 7.68 mg/(m²·h) and the average flux was 3.41 mg/(m²·h) from april to october.High salinity level inhibits the production and emission of CH₄, while low salinity promotes CH₄ production within certain range.In high-salinity conditions, CH₄ emission flux has a significant logarithmic negative correlation with salinity.In the early stage of growth of Phragmites australis, the flux of CH₄ is positively correlated with temperature and light; however, in the later stage of growth, it is negatively correlated with temperature and light.