By using static chamber and gas chromatography, the CO₂ fluxes from Carex cinerascens-dominated and Artemisia selengensis-dominated wetland in Xingzi County(in the Northern Lake Poyang)were measured during drawdown periods (from October 2014 to May 2015). Ecosystem respiration of the two wetlands showed an obvious seasonal variations, with the minimum value in winter and the peak value in spring,and the mean CO₂ flux for the Carex cinerascens-dominated and Artemisia selengensis-dominated wetland were 3291.80 and 2581.89 mg CO₂/(m²·h), respectively. The cumulative CO₂ fluxes were 213.71±2.27 and 176.39±11.48 t CO₂/ha for the two wetlands during drawdown periods, respectively. Furthermore, the higher CO₂ flux from Carex cinerascens-dominated wetland resulted from higher biomass. Soil temperature (5 cm) was the key factor controlling the seasonal variations of the CO₂ fluxes. The temperature coefficient (Q₁₀), an index of temperature sensitivity for respiration, was higher in Artemisia selengensis-dominated wetland, comparing to Carex cinerascens-dominated wetland. No significant correlations were found between soil moisture content and vegetation biomass and CO₂ fluxes.