Soil moisture, affected jointly by rainfall and groundwater, plays an important role in terrestrial water recycling. Hydrogen and oxygen isotopes can be used as tracers to study water movement and migration in the soil. Stable isotope compositions of soil water can be used to reveal information about a number of hydrological processes in soil, including infiltration, evaporation, transpiration and percolation, which is difficult to obtain by other techniques. The Loess Plateau in northern Shaanxi with loessal soil as its dominant type of soil, is arid in climate and scarce in water resource. Anumber of studies documenting tracer movement in the soil column except for using loessal soil to study soil water movement under differential recharge based on hydrogen and oxygen isotopes. Researches on soil water movement and migration in loessal soil may help understand characteristics of soil water movement, guide local agricultural production and improve water utilization efficiency in the Loess Plateau. A simulation experiment using soil columns was carried out in the State Key Laboratory of Northwest Arid Area Experimental Ecology and Hydraulic Engineering, Xi'an University of Technology. With the aid of isotope technology, exploration was done of temporal variation of soil water movement in loessal soil, temporal variation of distribution of isotope in soil water in the soil profile and relationship between oxygen and hydrogen isotopes in the soil water as affected by rainfall or groundwater, in an attempt to elaborate characteristcs of soil water movement in loessal soil relative to source of the recharge. During the experiment distributions of soil water content and hydrogen isotope in the soil profile were monitored 1, 3, 5, 10, 15, 20 and 30 days after the end of the recharge and relationship between oxygen and hydrogen isotopes in the soil water was fitted with a linear model. Results show that （1）being recharged with water from either source, rainfall or groundwater, the soil water increased in volumetric content as the time going on and leveled off in the end and that movement of the soil water obviously lagged behind. （2）Hydrogen isotope in the soil water was affected by source of recharge water, exchanging and mixing of the waters and evaporation of the water in the soil, and with the time going on, the effect of source of the recharge water gradually weakened, while the effects of exchanging and mixing of the waters and evaporation of the water in the soil gradually stood out. Eventually the soil water reached its dynamic balance. （3）When being recharged by rainwater or groundwater, soil water moved in a piston-driven way. With rainfall infiltrating into the soil, δD in the soil water first decreased, and then increased with increasing soil depth and eventually leveled off. The soil water in the surface 0~5cm soil layer was enriched in heavy isotope as a result of evaporation and the soil water in the 5~20cm soil layer stayed for the longest time, indicating that the soil layer is the highest in water retaining capacity. When being recharged by groundwater, the soil water decreased in δD with soil depth. The water in the upper soil layer was enriched in heavy isotope as a result of evaporation, and the water in the deep layer impoverished in isotope by recharge from groundwater. （4）Under either recharge modes, δD and δ¹⁸O in the soil water displayed a nice linear relationship. Isotope fractionation effect of soil water evaporation was greater when soil water was recharged by rainfall than by groundwater. Soil water recharged by groundwater tended to stay longer in the soil. Obviously, rainfall, groundwater and soil water evaporation all have some impacts on soil moisture. The variation of soil water isotopes with a certain regularity. So adoption of underground irrigation in the Loess Plateau region is conducive to preservation of soil water for agricultural production.