Based on the theory of H.T.Odum, a quantitative analysis of energy inputs and outputs of agri- cultural eco-economic system in Aba Autonomous Prefecture between 1952 and 2005 in Sichuan Province is given and an comparison of Aba with other regions is made.Results show that because of the over-exploitation of natural forest last century, ecological environment in the area has been seriously damaged.Along with the forest economy! ended and the rise of eco-tourism, Aba? s ecological and environmental conditions are gradually improved.But agricultural ecosystem still has such problems as serious shortage of modern assisted inputs, backward production model, and agricultural development on the basis of the excessive use of natural resources, so a sustainable development is difficult to achieve.It is therefore essential to enhance research and extension of agricultural science and technology, improve the quality of workers in order to make full use of local natural resources, increase the agricultural output capacity of ecological and economic systems, and achieve the sustainable development of agricultural economy.