Abstract: Using the eddy covariance technique, the Bowen-ratio meteorological and soil monitoring system, we analyzed the CO₂ flux dynamics and its responses to temperature and moisture over a meadow wetland in the Horqin during the growing season (from May to September) in 2016. The results showed that the accumulated net ecosystem CO₂ exchange (NEE) was -766.18 g CO₂·m^-2 during the growing season. The gross primary productivity (GPP) and ecosystem respiration (R_e) were 3379.89 and 2613.71 g CO₂·m^-2, respectively. The ratio of R_e to GPP was 77.3%, indicating that this ecosystem was an obvious carbon sink. The average diurnal variation of NEE exhibited a single peak U-shaped curve with an absorption of CO₂ from May to mid August and a release of CO₂ from late August to September. Daytime NEE well fitted with the photosynthetically active radiation (PAR) by a rectangular hyperbolic function. Meanwhile, the relationship was affected by the environmental factors, including vapor pressure deficit (VPD), soil water content (SWC) and air temperature (T_a). Regression analysis showed that the VPD and SWC for the maximum daytime NEE were 1.75 kPa and 35.5%, respectively. Daytime NEE increased with T_a, and with no inhibitory effect on the daytime NEE when it reached the maximum. Nighttime NEE had an exponential relationship with soil temperature (T_s). During the entire growing season, the temperature sensitivity of the ecosystem respiration (Q₁₀) was 2.4, which was negatively related to SWC. The nighttime NEE was controlled by both T_s and SWC.