[Background]Water is the major factor limiting plant growth on the water-wind erosion crisscross region of the Loess Plateau,which is being exacerbated by the precipitation reduction related to global climate change and the decline of groundwater level due to large-scale energy development such as coal mining and oil exploitation. How local vegetation respond to this decreased water availability is important for the understanding of their adaptation and survival in the future. [Methods] Using precipitation manipulation experiment (the contrast,+ 45% of precipitation by irrigation and - 50% of precipitation (Dry) by partial exclusion),the growths of different classes of branching shoots to varied simulated precipitations in Salix psammophila and Caragana korshinskii were studied during the second year of precipitation manipulation. [Results]1) For S. psammophila,the basal diameter,length and aboveground biomass of branching shoots within 10 - 15 mm class showed some responses to varied precipitation,the length and aboveground biomass of shoots with 15 - 20 mm class also presented certain responses,drought decreased the length and aboveground biomass of 10 - 15 mm class,and irrigation increased the length and aboveground biomass of 15 - 20 mm class. No responses for other classes of shoots were found. 2) For Caragana korshinskii,the radial growth of shoots with basal diameter < 20 mm presented significant responses to precipitation variation,but the responses of height growth of shoots were only found for shoots with basal diameter < 10 mm,suggesting a more sensitive response in smaller classes of shoots. Irrigation significantly increased aboveground biomass in shoots with basal diameter < 10 mm whereas drought did not decrease aboveground biomass of this class. For shoots with basal diameter of 10 - 20 mm,irrigation did not increase the biomass but drought significantly decreased the biomass. 3) Irrigation increased aboveground biomass per plant by 11.3% in S. psammophila and 35.5% in C. korshinskii, drought decreased aboveground biomass per plant by 14.2% in S. psammophila and 36.8% in C. korshinskii. [Conclusions] The results suggest that precipitation variation caused a greater effect on the growth of C. korshinskii than that of S. psammophila,and the growth of C. korshinskii showed a greater flexibility to varied precipitation,the reasons may be related with the differences of root water extraction source,soil infiltration properties and internal plant water redistribution,etc. These results may not only provide the insight of the adaptative mechanism how two shrubs cope with drought but also be conducive to forecast the growth dynamics and productivity of these two shrubs under future projected precipitation variation.