To study the effects of different collection methods on hydrogen and oxygen isotope values of soil water, a laboratory experiment is designed to model the rainfall infiltration behavior, and the water outflow from the bottom of the soil column is collected. In this experiment, soil waters at depths of 10 cm, 40 cm, 70 cm and 100 cm are collected and this collection method is termed as in-situ collection method. On the other hand, soil samples at the same depths are taken out with the soil waters being collected using vacuum distillation extraction method. The comparison results between D and ¹⁸O values show that during the process of rainfall infiltration in the dry soil sample, the light isotopes are preferentially adsorbed by soil particles, and the outflow water collected first has the most positive hydrogen and oxygen isotope values. The soil water extracted by the vacuum distillation method is composed of moisture-absorbing water of the air-dried soil and the water infiltrated into the unsaturated zone. The soil water collected by the in-situ soil solution sampler represents the water flowing in the soil and could be effectively used.