To explore the differences in water sources and dynamic changes of major plants in shrub communities under climate change, the response characteristics of water use sources and growth of typical natural recovery plants (Artemisia ordosica, Medicago Sativa and Chenopodium album) to drought stress in the Loess Plateau were studied. And the droughts were controlled by reducing natural precipitation by 15% (moderate drought) and 30% (extreme drought). The potential water sources of vegetation communities were divided into shallow (0—20 cm), middle (20—60 cm) and deep (60—120 cm) soil water. The stable water isotope technique and MixSIAR model were used to quantitatively analyze the water absorption characteristics of vegetation roots under different drought stress levels (30%, 15% and the control). The results showed that: (1) The stable hydrogen and oxygen isotope values (δD and δ¹⁸O) of soil water and plant water were both located at the lower right of the local atmospheric precipitation line, which indicated that the isotope of soil water was enriched by evaporation. (2) Water sources of three typical plants could be flexibly converted to different soil layers under drought stress, specifically, the proportion of shallow soil moisture utilization decreased, while the proportion of middle and deep soil moisture utilization increased, which became more obvious with the increase of drought stress levels. (3) Different vegetation responsed to drought stress through different water use strategy, Artemisia ordosica mainly used shallow soil water (contribution rates were 48.2%, 52.7% and 57.6%, respectively) under flat land, rainfall reduction of 30%, 15% and CK treatments, while Chenopodium album mainly used middle (43.5%), shallow (49.6%) and shallow soil water (53.6%), respectively. In slope land, rainfall reduction of 30%, 15% and CK treatment, Artemisia ordosica mainly used shallow soil water (contribution rates were 42.5%, 44.5% and 58.1%, respectively), while Medicago Sativa mainly used the middle (40.9%), middle (46.7%) and shallow (53.9%) soil water. This indicated that the main species of vegetation community in semi-arid loess hilly region could respond to drought stress by converting water sources through plasticity. And the community water sources were divided in space to effectively reduce the competitive pressure on water resources, which would promote the coexistence of species through niche differentiation in water resources utilization.