Evaluating the value of ecosystem services is an important indicator to measure the development status of grassland ecosystems. Quantitative analysis of dynamic changes in ecosystem service values is of great significance to protect grassland resources. This paper used MODIS images and annual precipitation data from 2000 to 2015 to build a quantitative system for evaluating the value of ecological services of Xilingol League. The values of six service functions of grassland ecosystem, namely, product provision, nutrient cycling, carbon and oxygen balance maintenance, water conservation, soil maintenance, and entertainment, were calculated and dynamic changes in each banner, city and county of the research area were discussed. The results show that the total service value provided by the grassland ecosystem in Xilingol League from 2000 to 2015 exhibited a fluctuating increasing trend, with a 2.52% annual growth rate and increasing 3.371 billion yuan. However, the development of grassland resources among banneres, cities and counties was imbalanced (annual growth rate range from -0.46% to 1.71%), and even showed negative growth in service value in Zhengxiangbai Banner (annual growth rate was -0.30%) and Taipusi Banner (annual growth rate was -0.46%). The value derived from service functions provided by grassland ecosystem varied greatly. The function of maintaining carbon and oxygen balance accounted for 35% of the total value, while product provisioning accounted for only 5%, and the function of water conservation, which played a vital role in the protection of grassland ecosystem only accounted for about 1.5%. This research will provide a reference for the dynamic estimation of grassland ecosystem services in Inner Mongolia Autonomous Region and even Beijing-Tianjin-Hebei region.