Hydroenergy is a kind of clean and renewable energy sources. As a high-quality energy source, it plays a key role in realizing the strategy of sustainable development. With consideration of the abundant hydropower resources in China, giving priority to its development becomes an important policy of China's energy resources exploitation. The development and utilization of hydropower resources may decrease the yield of coal and the environment pollution caused by thermal power generation. However, damming a river will lead to the change of water-sand regime, which will exert adverse impact on the ecosystem and environment. As a result, countermeasures should be studied and taken to well deal with the relationships between the hydropower development and the environmental & ecological protection. The development and exploitation of hydropower should be based on the comprehensive planning of a river basin and carried out in a scientific, reasonable, appropriate and orderly way. Moreover, it is necessary to reasonably combine hydropower development, environmental & ecological protection and promotion of regional economic & social development, so as to make the relevant work go smoothly, such as resettlement for reservoir areas, improvement of migrants' living and productive conditions and promotion of harmonious development between economic construction of reservoir areas and environment protection.