Over the last two decades, the great progresses have been made in the application of RS and GIS in hydrology. Especially, from several years ago, an integration of RS and GIS with hydrological models had become technically feasible, so the studies on hydrology came into a new era. This paper reviews on the roots of hydrological GIS, the application of RS and GIS in hydrology and review on the integration of RS and GIS with hydrology. It can be concluded that: In the future, hydrological modeling will be more global, more distributed, and more sophisticated. In this situation, the integration of RS and GIS with hydrology will not only speed up the research on hydrological but also play a great role in water resources management.