By the analysis of soil moisture profile of 10 m deep it shown that there is very abundant soil water resources (SWR) on Loess Plateau, SWR amount in the 3~10 m depths is 1 086.8 mm in the south and 524.1 mm in the north on Loess Plateau. SWR amount of various sites is about two times of rainfall amount in the same sites. There was a fluctuation and relatively steady of soil moisture change with soil layer deep. By comparing soil moisture of the control sites with artificial forest land it was found that mainly artificial tree types in Loess Plateau could take up soil moisture from 9~10 m deep soil layer and caused the dried soil layer of 3~8 m soil layer, of which soil water content is nearly to or lower wilting point during longterm. Dried Soil layer was a special phenomenon of eco-hydrology and also was an indicator the instability of artificial forest vegetation on Loess Plateau. It shown that artificial forest vegetation did not currently has function to conserve water supply on Loess Pleatu.