In soil erosion areas of southern China, it is difficult to grow trees and grasses for soil and water conservation in summer and autumn as temperature is too high and water content is too low. To determine suitable water situation of soils and to decide the optimum depth for planting and seedling, stationary observation of the water content of three soils under different vegetation was carried out during April to September of raining season. The results were shown that the change of water content under 30cm in the profile is stable in soils derived from quaternary red clay and purple shale during experimental period, while the marked variation are occurred in soils from granite moreover, mulches may show important effect on the improvement of the capacity of soil reserving water. Finally, proposals to enhance survived rate of the seedliog in granitic soils were advanced.