The maintainence and conservation of ecosystem service is an important basis for the sustainable development, especially under the context of global climate changes.In this study,we precisely evaluated the value of ecosystem service(ESV)and then quantified the effects of climate factors on the ecosystem service in the Xilinguole National Nature Reserve in Inner Mongolia,China.Based on the unit area method with remote sensing products of value evaluation of ecosystem service from1985to 2014.Our results showed as follows:(1)The area of grassland decreased during the past 30 years,and ESV of the nature reserve also showed a decreased tendency by 1.8 billion at least every ten years;(2)ESV was very sensitive to the climate changes,52.5%of the inter-annual variations of ESV was caused by temperature and precipitation at least;(3)The existing ecological protection of the nature reserve can offset the effects of climate changes on ecosystem service in some degree. Our results provides more reliable data basis for the establishment of the ecological compensation mechanism for nature reserve area and enaction of reasonable strategies of ecological protection of biodiversity.