Abstract: Yishui County,which has more mountain land,less farmland and severe soil erosion,lies in the Taiyi mountain area and is a poor county of economy in Shandong Province. Base on the datas of 31 towns in Yishui and the ten indexes choosed, the author utilized grey constellation clustering method and studied the agricultural ecological economy of the whole county. It provided a scientific basis for the farmers of the poor mountain area to become rich and for the harmonizing developmend of society, economy and ecology as well as agriculture sustainable development.