Through the preliminary study of soil moisture in loess hilly areas of the West Inner Mongo-lia, it was concluded that the dynamic distribution of soil moisture in vertical direction can be di-vided into three section, i. e., the fluctuation section (0 - 40cm), the middle transformation section(40- 100cm), the relative stable section (100 - 200cm). There is agreement between the dynamicchanges in soil moisture and the changes in rainfall in arid farmland.