Abstract: In ordor to study the isotopic variations of different water bodies in soil water evaporation and rainfall infilltration processes, two different soils-sand and loess were chosen and two indoor experiments were designed. The analysis of and values showed that the isotope fractionation of soil water obeyed the Rayleigh model in the process of water evaporation for sand. But for the loess, the isotopic compositions of the residual soil water were away from the Rayleigh line along with the increasing of evaporation time. In the early stage of rainfall infiltration, the isotopes of outflows were affected by the air dry loess grain, which was different from the air dry sand. And the values of outflows were also affected by isotopes of the initial soil water. Only when the infiltration amount reached a certain one, the outflow could represent the isotopic composition of rainfall. The results of this study can provide data analysis basis of relationship between local rainfall and groundwater based on isotopic variations.