Agro-ecosystem is very important to our human beings, but the fact is we know veryless about its ecosystem services.So this study selects barley agro-ecosystem of Dazi County in Lhasa-river valley and uses different methods (such as market value,substitution engineering,shadow price)to calculate its value.The result shows that the total value of barley agro-ecosystem services is 37 249.77×104 yuan;the order of various ecosystem services values is respectively production value16 973.38×104 yuan(45.57%),release of O2 10 649.81×104 yuan(28.59%),fixation of CO2 7 875.03×104 yuan(21.14%),nutrient circle maintained 1 478.23×104 yuan(3.97%),and water holding 273.32×104 yuan(0.73%).So agro-ecosystem provides great ecological services to its economic productivity,but the production service is its most important service.