Inner Mongolia comprises 22% of the grassland ecosystems in China and plays an important role in the global budget of the greenhouse gas (CO₂, CH₄, and N₂O). In this study, we compiled the data of greenhouse gas fluxes and related environmental factors from 34 sites in Inner Mongolia collected between 1995 and 2012. The annual flux of greenhouse gases or flux over growing season differed greatly between meadow steppe, typical steppe, and desert steppe. Typical steppe and desert steppe emitted CO₂ at rates of (20.64 ±11.54) mgC m^-2 h^-1 and (18.04 ±2.48) mgC m^-2 h^-1, respectively, whereas meadow steppe absorbed CO₂ at a rate of (10.31 ±1.15)mgC m^-2 h^-1. Meadow steppe, typical steppe, and desert steppe absorbed CH₄ at rates of (30.48 ±9.57) μgC m^-2 h^-1, (41.25 ±3.61)μgC m^-2 h^-1, and (85.00 ±51.03)μgC m^-2 h^-1, respectively. They emitted N₂O at rates of (28.40 ±7.27)μgN m^-2 h^-1, (3.18 ±0.91) μgN m^-2 h^-1, and (2.51 ±0.67)μgN m^-2 h^-1, respectively. Correlation analysis of the fluxes and environmental factors from typical steppe showed a positive correlation between the averaged CH₄ absorption flux and precipitation (P < 0.05), soil moisture (P < 0.05), and soil temperature (P < 0.05). The averaged CO₂ flux was negatively correlated to precipitation (P < 0.01), soil moisture (P < 0.01), and leaf area index (P < 0.01) and positively correlated to air temperature (P < 0.01). Meanwhile, N₂O flux was positively correlated to precipitation (P < 0.05), soil moisture (P < 0.05), and air temperature (P < 0.01).