Global temperature and precipitation are undergoing unprecedented change, which has seriously affected the structure and function of steppe ecosystems in Inner Mongolia. The vegetation of this region has been suffering from severe salinization, desertification, and decline in productivity, resulting in severely ecological problems and economic losses. Although numerous studies indicate that desertification is intensifying currently, but the history of vegetation cover and geographical distribution patterns of vegetation are poorly understood. This research attempts to simulate the temporal and spatial changes in the geographical distribution of steppe vegetation based on MaxEnt and changes of net primary productivity (NPP) based on synthetic model in Inner Mongolia during 1961 to 2010. The aim of this research is to provide a valuable method for predicting the potential impact of climate change on vegetation in the future. The results show that moisture index (MI), annual precipitation (P), mean temperature of the warmest month (T_w), and mean temperature of the coldest month (T_c) are the dominant climatic factors determining the geographical distribution of steppes. The MaxEnt model performs well in simulating the geographical distribution of steppe vegetation in Inner Mongolia. The AUC of meadow steppe, typical steppe, and desert steppe are about 0.90 (excellent), 0.85 (very good), and 0.95 (excellent), respectively. The kappa consistencies of meadow steppe, typical steppe, and desert steppe are about 0.95 (excellent), 0.70 (very good), and 0.57 (very good), respectively. The overall kappa value of the entire steppe vegetation is about 0.76 (very good). The areas characterized by steppe vegetation in Inner Mongolia have shrunk during 1961 to 2010. The distribution area decreased to about 5% for meadow steppe, 1% for typical steppe, 62% for desert steppe, and 11% for the entire steppe. The gravity centers of both meadow steppe and typical steppe have moved towards southwest, while the desert steppe moved towards southwest on the initial stage and to the northeast later. Due to these shifts the entire range of steppe are confined within narrow distribution boundary. The area converted from meadow steppe to typical steppe (2.38 × 10⁴ km²) is less than the area of transformation of the latter to the former (3.57 × 10⁴ km²). The area transformed from desert steppe to typical steppe accounts for 15% of the total area of desert steppe. The change in areas shows that the Inner Mongolia steppe is undergoing desertification. The NPP of the entire steppe, meadow steppe, typical steppe, and desert steppe were 312 gDWm^-2a^-1, 341 gDWm^-2a^-1, 309 gDWm^-2a^-1, and 260 gDWm^-2a^-1 in Inner Mongolia during 1961 to 2010. The change in NPP of the entire steppe followed a decline-increase-decline trend during 1961 to 2010. Regional precipitation is the primary determining factor for the NPP of steppes in Inner Mongolia. The MaxEnt model is one of the bioclimatic envelope models (BEMs) based on the niche theory. BEMs are often used to solve problems in conservation biology, biogeography, ecology, and taxonomy at species level. We have successfully used the MaxEnt model to simulate the geographical distribution of the different steppe vegetation types. This study extends the range of application of BEMs, which has facilitated the understanding of the functional diversities of ecological systems and advanced classification units (above the individual and community level).