Abstract: The emission fluxes of methane and carbon dioxide were tested at cover layer of one MSW landfill in Beijing for one year. The seasonal and diurnal variation of methane and carbon dioxide emission fluxes at MSW landfill sites was analyzed, and the correlation of methane and carbon dioxide emission fluxes as well as the influencing mechanisms explored. The result shows that there exists big imparity among methane emission fluxes at 10 monitoring sites or at the same point for different time. The seasonal variation of methane emission at different sites may fluctuate with the carbon dioxide emission fluxes, showing a significant correlation, or the methane emission fluxes may have a small fluctuation in spring, summer and autumn, but fluctuate with the carbon dioxide emission fluxes in winter. The diurnal variation of methane emission fluxes shows no regularity. The methane content in atmosphere has a significant influence on the methane oxidation in the landfill cover.