According to data of overland flow from runoff plots which represent various rainfall collecting and data of soil moisture from determined positions periodicaIly,the relationship between soil moisture envoirnment and water-harvesting afforestation techniques and rainfall utilization of trees,water balance on afforested lands are analysed in semi-arid loess region-The results show that water-harvesting for afforestation greatly increase rainfall use efficiency of trees and also improve the c0ndition of soil moisture.