The basic concept and recent research progress of Digital Basin (DB) are introduced in the light of the strategic demand of water resource development in the new era. Key technologies inclusive of the basic framework and technical standards, the comprehensive observation system involving space, air, and ground data, the organization, processing and sharing of multi  source mass spatio  temporal data, and multi  disciplinary model integration and application are discussed in detail. The practices of applying digital basin to the operation and management of Three Gorges Project are analyzed. The applications are summarized and looked forward.