To assess the impacts of mowing on N₂O and CH₄ fluxes emissions from the meadow-steppe grasslands of Inner Mongolia, China, two regimes were investigated: unmown since 2005 (UM), and mown once every three years since 2009 (M3). On-site measurements were conducted continuously during a year-round period (August 2011 to August 2012). During the observation period, three diurnal cycles were also measured. In addition, a targeted laboratory experiment was conducted to make up for the few measurements in winter. A large pulse of N₂O emissions related to freeze-thaw cycles was observed at M3 during the spring thaw. Results showed that the meadow-steppes played a role as a sink for CH₄ and a source for N₂O. Significantly lower mean CH₄ uptake at UM (40.3 μg C·m^-2·h^-1) as compared to M3 (70.5 μg C ·m^-2·h^-1) (p<0.01), and significantly higher mean N₂O efflux at UM (6.3 μg N·m^-2·h^-1) as compared to M3 (4.3 μg N·m^-2·h^-1) (p<0.05) were found. The laboratory experiment results revealed that mowing changed the soil conditions that favor the activity of denitrifiers during thawing periods. The CH₄ and N₂O fluxes were significantly correlated with soil temperature (p<0.05). Mowing affected CH₄ uptake and N₂O emission mainly through its effect on vegetation types and some soil properties, such as soil inorganic N content, soil temperature, and soil moisture content, while soil inorganic N and moisture were not leading factors. Our results also suggested that mowing could mitigate the potential global warming in terms of CH₄ uptake and N₂O emissions.