A large amount of climatic,soil and vegetation data were collected from animal husbandry meteorological station and ecological meteorological observatory. Based on those information,temporal and spatial variations of grazing capacity in Inner Mongolia grassland during the 1961 - 2010 were simulated by CENTURY model, and correlations of grazing capacity and key meteorological factors were analyzed. Research results showed that proper grazing capacity was 0.74 - 1.60 sheep unit /hm~2oa for different grassland types in Inner Mongolia. In the past 50 years Inner Mongolia grassland grazing capacity,on the whole,slightly increased,but increasing trend was not significant. Thereinto,grazing capacity increased in mediate temperature meadow steppe,decreased in mediate temperature typical steppe,variation tendency was not obvious in other grassland types. Spatial difference of grazing capacity was obvious in Inner Mongolia grassland,high - value area was mainly distributed in forest steppe transition zone in the eastern of Daxinganling,and the grazing capacity was 1.7 ~ 2.0unit / hm~2·a. Low - value area was mainly distributed in the mid - west north pastoral areas,the grazing capacity was below 0.8unit /hm~2·a. Correlation analysis showed that the precipitation still was the most direct meteorological factor impacting on grazing capacity.