Abstract: Deep-buried water conveyance tunnels often traverse complex geological environments and challenging terrains, while conventional investigation methods exhibit deficiencies in terms of accuracy, capability, and safety. To explore more efficient and reliable investigation techniques, this study systematically reviewed the research progress and existing challenges of directional drilling technology in water conservancy engineering exploration from the demand of water conservancy engineering for the technology, directional drilling coring technology, integrated logging technology, borehole camera technology, and hydrogeological test methods. Typical engineering application cases were analyzed, and the future development trends and research directions of directional drilling technology were discussed. The results indicated that directional drilling technology transforms traditional "point-based" investigations into "line-based" investigations, providing a novel approach for deep-buried water conveyance tunnels. Future research should focus on technological innovation and the improvement of equipment performance to promote the widespread application of this technology in water conservancy engineering exploration.