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As the main solid waste disposal method in China, landfill sites are considerable sources of methane (CH 4 ) and carbon dioxide (CO 2 ). This study characterized the seasonal variation of CH 4 and CO 2 effluxes at a large and well-managed final covered landfill site in China. A three-year monitoring program was conducted. There were two different seasonal variation patterns for hotspot and non-hotspot' CH 4 and CO 2 effluxes. For non-hotspots, the CH 4 and CO 2 effluxes' seasonal variations were mainly affected by the seasonal change of the landfill's cover soil respiration activity, particularly the CH 4 oxidation capability. CH 4 had a higher efflux in winter; in other seasons, the CH 4 efflux fluctuated around 0; the CO 2 effluxes were (1) increased in spring and peaked in summer or early autumn; (2) then, they decreased to a minimum value in late autumn or early winter; and (3) fluctuated with the CH 4 efflux in winter. The CH 4 emissions in winter account for 60.4-84.4% of the all year outputs. For the hotspots', the CH 4 and CO 2 effluxes seasonal variations were mainly determined by the seasonal change of the landfill cover's soil gas permeability. The ratio of CH 4 emissions in winter to the all year outputs range from 17.4 to 68.7%., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)