Abstract: To investigate how soil respiration and heterotrophic respiration respond to rainfall changes and increased nitrogen deposition during the freeze-thaw period is important for accurate prediction of soil carbon dynamics in terrestrial ecosystems in the context of future global change. A field simulation experiment of increased rainfall (15% of multi-year average rainfall) and nitrogen deposition (25 kg ha⁻¹yr⁻¹) was conducted in a typical temperate grassland in Inner Mongolia to analyze the daily variations of soil respiration and heterotrophic respiration during the freeze-thaw period under changing water and nitrogen conditions . The maximum values of soil respiration and heterotrophic respiration flux (CO₂ emission rate) occurred in the afternoon when the temperature was highest or in the morning after the occurrence of soil freeze-thaw, and the minimum values occurred at night when the temperature was the lowest. The increase in respiration flux caused by water and nitrogen was not significant (P > 0.05), but the elevation in cumulative soil respiration fluxes induced by water and nitrogen were about 145 mg m⁻² and 70 mg m⁻² during the two diurnal observation dates in autumn and spring, respectively. Due to the high proportion of heterotrophic respiration in soil respiration (> 70.3%), the stimulation of daily cumulative flux of heterotrophic respiration induced by water and nitrogen in autumn and spring was close to that of soil respiration. The correlation between respiration flux and soil moisture, nitrogen nutrient content, and 5 cm and 10 cm ground temperature was not significant (P > 0.05); and the correlation between respiratory flux and air temperature and surface soil temperature was significant, showing a significant quadratic nonlinear fit (P < 0.01), where air temperature explained 53% to 84% of the daily variation of respiratory flux. Air temperature and 0 cm soil temperature were the main factors controlling the daily variations of respiration fluxes, and the positive effect of increased water and nitrogen on the daily cumulative fluxes of soil respiration and heterotrophic respiration should not be neglected.