Hydrological drought is an important type of the natural drought, and it involves many factors in regional water balance, affects the evaporation, infiltration and runoff three processes in water cycle in the world, and it relates to the water cycle and wa - ter balance. The current research on drought pay more attention to meteorological drought and agricultural drought, considering the importance of hydrological drought and less focus on hydrological drought, the research on hydrological drought has been classified and summarized in this paper, the problem and the main development direction on hydrological drought has been presented, which may give guidance to deep research.