The δ18O and δ2H showed significant correlations in plant water, precipitation, and soil water during the study period (Figure 5). The local meteoric water line (LMWL) was described by equation, δ2H =7.89 × δ18O +17.79 (R2 = 0.97; p < 0.05) , its slope was smaller than the global meteoric water line (GMWL), δ2H = 8.17 × δ18O + 10.35; (Rozanski et al., 1993), indicating that evaporation is a main reason of arid climate and kinetic fractionation in the research sites. The linear relationships of δ18O and δ2H in soil water were significantly indicated that the different evaporation effect between shrub and grassland sites. Additionally, their slopes and intercepts at the two sites were smaller than those of the LMWL, for the ongoing evaporation influence soil water (Yang&Fu, 2017). Moreover, Soil water, plant water and LMWL laid at an angle on the both sites, indicating that these water types contained water that had been recycled through terrestrial evaporation and precipitation.