A review on the current situation of researches on soil water resource is presented.Based on t he concept of characteristics, a new definition of soil water resource is suggested.It has been pointed out that the soil water resource are defined as the renewable amount of soil water resources, which can be directly uti- lized for plants including crops and soil microbes at the depth where plant roots can absorb soil water.The article also expounds the characteristics of soil water resource, such as dependence on recipitation, easy consumption, beyond exploitation, validity or unavailable usability on site, and possibilit y to be controlled.The index system established for assessment includes four indexes: maximal stock of soil water resource, available quantit y of soil water resource, unavailable quantity of soil water resource, and the amount of actual storage.According to the assessment indexes, preliminary calculation for a typical area in the loess hilly area is performed.