Soil water environment of 0-15 m loess profiles in bare land, high-yield farmland, alfalfa grassland and apple orchard on the Changwu Loess Tableland are investigated based on the data of long term experiments in situ. Results show that the seasonal variations of soil water were obvious in the layers of dry-wet alternation and the depths that the layers appeared were different under different land use patterns. The depths for bare land, high-yield farmland, alfalfa grassland and apple orchard were 0-5 m, 0-4 m, 0-2 m and 0-3.5 m, respectively. Soil water in deep soil layers below the layers of dry-wet alternation was mainly affected by land use patterns. In terms of the magnitudes of the effect, it showed in the order of alfalfa grassland > apple orchard > high-yield farmland > bare land. And the temporal variations of soil water in deep soil layers were different under the different land use patterns. The determination of soil thicknesses is very important to the calculation of soil water balance on the Loess Tableland, depending on the land uses and the growth stages of the vegetations. The calculated soil thicknesses should be 5 m and 4 m at least in bare land and high-yield farmland, respectively and be 15 and 10 m at least alfalfa grassland and apple orchard, respectively when the stable dry soil layer has not yet formed in soil profile. However, when the layer has formed in planted woodland and grassland, the calculated thickness can take the depth of precipitation infiltration in the analysis of soil water balance at annual scale. This study can improve the sustainable development of rain-fed agriculture and the optimal allocation of landuse patterns in the aspects of the conservation and utilization of soil water resources for the Loess Tableland.