The biodiversity of fish in the Yangtze River valley is of great value for the ecology, economy and scientific research as it is characterized with a great variety, abound resources, high peculiarities and various economic species. But its population tends to go down obviously due to so many threatening factors like the fish-migrating barrier, habitat deterioration and water regime change as a result of the river cascade exploitation,i. e. hydraulic works. In order to protect the biodiversity of fish, it is quiet necessary to upgrade the engineering concept and technology for the planning and design of hydraulic works, and build up necessary fish passage facilities like fishway for the reservoir ecology operation, and also essential to create the natural fish reserve and establish an ecological compensation mechanism etc.