[Objective] Studying of dynamic characteristics of soil water in the gully region of Loess Plateau is very important to provide supports for the constructions of forest

ecological restoration and management of Platycladus orientalis.[Methods] Sites of 5

25 and 35 a Platycladus orientalis in typical small basin(Nanxiaohegou basin) in the gully region of Loess Plateau were selected

where the soil moistures in growing season were observed with drying method. On the basis of this

the spatial and temporal distributions of soil moisture in different layers and the desiccation characteristics of each layer were analyzed.[Results] ① The rainfall recharged depth on soil moisture of the Platycladus orientalis concentrated in 0-40 cm while the effect of Platycladus orientalis' roots on soil moisture concentrated in 40-100 cm. ② The temporal variation of 0-100 cm soil moisture during growth season can be divided into recovery period(May) and depletion period(Jun. to Sept.). In the recovery period

the age of the Platycladus orientalis had little effect on soil water distribution. The water storages of 5 a

25 a and 35 a Platycladus orientalis in 0-100 cm varied between 230.3~304.2 mm

177.7~249.7 mm and 202.2~283.6 mm

respectively. In the depletion period

the soil moistures of 10-40 cm in different sites ranked:5 a > 35 a > 25 a; while in 60-100 cm

the rank was 5 a > 25 a > 35 a. The 3 sites' water storages of 0-100 cm varied between 131.2~207.2 mm

123.4~220.8 mm and 109.6~204.7 mm

respectively. ③ In the recovery period

there was little difference for the SDIs among different soil layers; while the SDIs in the active layer and transition layer of 25 a and 35 a sites increased with the increase of depth. For root affected layer

its value was relatively stable. In the depletion period

SDI value of the Platycladus orientalis was smaller in the active layer and increased with the increase of depth in the transition layer. For the root layer

the value was relatively stable.[Conclusion] As compared with it in the recovery period

the change degree of soil moisture increased significantly in the depletion period

and the absorption capacity of root increased in older Platycladus orientalis site.