Abstract: Through the analysis of situation of agricultural eco-economic system at Wangdonggou watershed in gully region of loess plateau between 1985 and 2005, it has been discovered changed greatly, and used the developing process of population, agricultural land, fruit land, forest land, grassland, yield of grain 6 key economic indexes divided the evolutionary process of agricultural eco-economic system into 3 different stages, and discussed the characteristics of different stages. On the base of the problem analysis on the stages, it forecasted the possible developing trend.