Abstract: The agriculture ecosystem not only provides products, but also a myriad of indirect ecosystem services. Based on environmental economics and GIS technology, this paper evaluated ecosystem services such as products provision, climate regulation, soil conservation, carbon fixation, O₂ release and nutrient maintenance by agriculture ecosystem of Manas River Watershed for 1976 and 2005. From the study, there is an increase in total value of ecosystem services from 352 219.4×10⁴ yuan in 1976 to 767 061.5×10⁴ yuan in 2005, representing a 117% increase over the 29-year period. The products provision value to total value ratio increases from 7% to 39%, implying that technology and management influence products provision. There also exists a great potential for improving the amount of products in the region. Regarding indirect agricultural ecosystem services value, the nature of the attributes represents enormous regulation and support services. For the period of study, indirect agricultural ecosystem services value increases by 43%. The study of agricultural ecosystem services in Manas River Watershed indicates myriad ecosystem services besides agricultural products provision. To attain harmonious development of the society, economy and nature ecosystem in arid watersheds, agricultural ecosystem services value should be accorded paramount importance.