Soil water is one of the most important water resources of ecology and many hydrological elements. The Loess Plateau locates on the arid and semi arid area. Because distribution of annual rainfall amount year by year, are cruelly nonuniform, soil water resources are basically important on the growth and development of plants. At the same time distribution and amount of soil water resources are impacted by human action. Soil and water conservation (SWC) in the Loess Plateau is major projects which human transforms the ground layer characteristics and it has impacted on the amount distribution and dynamic progress of the soil water resources. Engineering measures of SWC on the hillslope can improve soil water content. Many kinds of the artificial vegetation which have deeply root systems could decrease the soil water content in their lands, and even formed the drought layer of soil water. To contrast with the artificial vegetation, the natural vegetation, which had higher production, did not degenerate soil water status. That problem is worth further researching for the eco environment construction in the Loess Plateau in China.