Abstract: The contrast date and great changes from comparing the two investigations of the agricultural eco-system in the Loess Plateau conducted in 1981,and fifteen years later in 1995 proved that the eco-agricultural construction is a correct strategic choice of sustainable development of agricultural construction is a correct strategic choice for sustainable development of agriculture in China. A case study was carried out in Yan'an City, one of the fifty pilot counties for eco-agricultural construction in China .Principles and benefits of its seven projects of eco-engineering are analysed which showing the feasibility and sustainability of eco-agriculture,which is a good way suitable to national conditions of China and can enable the environmental improvement and agricultural production to co-develop.