Based on the investigation on and soil water loss in Xingguo county,Jiangxi province,some factors of natural and social economical causes are analyzed,the man-made social economical factor is recognized as the main factor and some points are put forth that the harness and management of watershed should be abided by ecological economical level and set forth an energy record in theory for the harness of watershed in south China and proof of land desertification in northwest China.The ecoenergy system plotted in the harnessing of water-shed could strengthen the achievement in harnessing before done and alleviate the effect by human being,so the eco-energy system is an effective method for us to control the water and soil losses in the social ecological economical system.