Abstract: According to the two water worlds hypothesis (TWW), there are two independent water pools with different functions in the soil matrix, bound water world used by plants and mobile water world contributed to runoff and groundwater recharge. The TWW hypothesis is different from the original hydrological model that soil water is completely mixed, and is of significance for establishing new hydrological models. Currently, the theorical basis and formation conditions of TWW hypothesis are still unclear, with less reaserch from China. Here, we summarized research process, discrimination method, controversial points and prospect of TWW hypothesis. There are three views regarding the hypothesis: support, partial support, and rejection. All evaluation methods are based on hydrogen and oxygen isotope (²H, ¹⁸O) methods, such as direct comparison, precipitation intersection point method, precipitation residual method, and precipitation migration method. The representativeness of isotope samples of bound water and mobile water and the limitation of isotope technology may be the important reasons for different results across all the studies. The development of methods different from stable isotope ones is an important direction of future research. In addition, the theoretical basis of TWW hypothesis remains unclear, which is the most critical issue. The hypothesis is about a continuous ecological hydrological process coupling of precipitation, soil, and vegetation. Multi-disciplinary integration, multi-scale assessment and multi-factor analysis would be the effective ways to study this hypothesis, and would be an important research direction in the field of hydrology and ecology.