Salix cheilophila is a typical afforested shrub species that is widely used as the sand-binding shrub in alpine and semi-arid sandy land. Research on water use source of S. cheilophila helps to understand the stability and maintenance of the artificial ecosystem of desert sustainable development. In the sandy land at east shore of the Qinghai Lake, we took S. cheilophila growing on different geomorphology of the dunes (windward slope, dune top, and leeward slope) as objects to analyze water use source during the plant growth season by IsoSource isotope mixing model. The results showed that S. cheilophila mainly absorbed three layers of soil water during growing season in 2018, and individuals among different topographic positions used different layers of soil water in different growing seasons. At the beginning of the growing season, S. cheilophila on the windward slope primarily depended on deep soil water in 60-120 cm depth and the proportion was (50.28±18.11)%, while individuals on the top of the dune and the leeward slope used (79.96±7.59)% and (53.47±6.47)% surface soil water of 20 cm depth. In the middle of the growing season, S. cheilophila on the windward slope absorbed (45.52±26.91)% the middle layer of 20-60cm soil water, however, S. cheilophila on the top of the dune and leeward slope took up (45.17±20.14)% shallow 20 cm soil water and (39.26±23.28)% deep soil water under 60 cm soil depth, respectively. At the end of the growing season, S. cheilophila on the windward slope still used (46.07±27.17)% middle layer of soil water, and individuals on the top of dune transferred to rely on (44.25±26.23)% deep soil water, while S. cheilophila on the leeward slope switched to take up (42.57±18.78)% surface soil water as main water source. The differences in water use patterns are closely linked with the range of the active root zones and soil water content along different micro-topography conditions. This study can provide insight into plant-water relations to facilitate the selection of woody species for afforestation and desert restoration management in the semiarid desert region.