Water conservation function is an interdisciplinary study topic of both ecology and hydrology, which has gained numerous studies in recent years. Water conservation function encompasses a wide range, and the water conservation capability is a quantitative assessment of the specific research objects based on the characteristics of different research areas. Water conservation capacity is defined as the maximum water holding capacity of an area, which is related to the regional climate, soil, vegetation and other factors, and the water held or stored in the area can replenish surface runoff or groundwater, and provide relatively stable water supply for the regional industrial and agricultural development. The composition and influencing factors of regional water conservation capacity are discussed, and the influence of climate conditions and human activities on water conservation capacity under changing environment is analyzed. In addition, the characterization of water conservation capacity is different in arid and humid regions. Based on the above point of view, the applicable conditions and advantages as well as disadvantages of each assessment method of water conservation capacity are summarized. On this basis, the direction of water conservation capacity assessment is discussed in order to provide a scientific reference for the development of ecological hydrology as well as environmental governance.