In recent years, the Chinese government has carried out a series of vegetation restoration work to prevent soil erosion on the Loess Plateau. Understanding the water use strategy of afforestation vegetation is very important for effective vegetation restoration in arid and semi-arid Loess Plateau region. However, unreasonable afforestation activities cause damage to soil moisture environment, resulting in low survival rate, low preservation rate and low comprehensive benefit of vegetation. The key to the problem lies in the use of water consumption strategy in the process of vegetation restoration. In this study, Caragana Korshinskii and Hippophae rhamnoides were were selected as the research objects for large-scale afforestation in Anjiagou small watershed of Dingxi City, Gansu Province. We measured sap flow in the branches and stems of shrubs using sap flow gauges (Flow32, Dynamax Inc., Houston, TX, USA), and studied the response of sap flow density to the environment factors. The results showed that the effect of rainfall on water content in 10 cm soil layer was more obvious than that in the other three soil layers. Soil water content and coefficient of variation were relatively low in deeper layers. The soil water content in 10 cm soil layer responded to rainfall events with accumulated rainfall over 10-12 mm in 3-5 days. For the soil depth of 20, 30, 40 cm and 50 cm, a single rainfall less than 10 mm had little effect on soil water content. The average daily sap flow densities of C. korshinskii and H. rhamnoides were 1553 kg m^-2 d^-1 and 1760 kg m^-2 d^-1, respectively. In most cases, higher sap flow densities were consistent with higher values for Q₀ and D_z. For example, on 30^th June and 15^th July, the sap flow densities of C. korshinskii and H. rhamnoides were 3129.88 and 2772.81 kg m^-2 d^-1 and 3264.04 and 3234.32 kg m^-2 d^-1, respectively. For example, on 14^th June and 5^th September, the sap flow densities of C. korshinskii and H. rhamnoides were 923.11、1140.24 kg m^-2 d^-1 and 552.15、571.24 kg m^-2 d^-1, respectively. In the period of rainfall, the decrease range of sap flow densities becomes higher. There were different responses of sap flow density to weather conditions. Sap flow density in C. korshinskii and H. rhamnoides was the result of the vapour pressure deficit, photosynthetically active radiation and air temperature in August, and the sap flow density mainly depended on the vapour pressure deficit. But the sap flow density was the result of the vapour pressure deficit and photosynthetically active radiation in other months. When C. korshinskii and H. rhamnoides experienced long-term drought and no rain, soil moisture content had a great influence on sap flow, and D_z and Q₀ were no longer the main factors affecting sap flow density. On cloudy days after rainfall, sap flow still maintained a large density, which was due to the long-term soil water stress of vegetation growth in semi-arid areas. Rainfall enhanced soil water and had a pulse effect on sap flow density. The density of sap flow of H. rhamnoides is higher than that of C. korshinskii, which reflects that H. rhamnoides consumes more water under the same rainfall condition. As for the two shrubs, C. korshinskii has more advantages in vegetation restoration on the Loess Plateau. This study can provide necessary scientific basis for vegetation restoration on the Loess Plateau.