Abstract: Digital twin wateshed is to build the response relationship between natural factors of watersheds and management business, based on the three- dimensional geographic information digital baseboard, coupled with hydrological, hydrodynamic and other professional models, combined with data- driven machine learning and other technologies, so as to realize the four flood prevention functions (forecasting, early-warning, drill and emergency plan, FEDE) of watersheds., and provide technical support for watershed management and high-quality development. The Pearl River Delta Basin has a dense water network. The rapid development technology of digital twin small watersheds can effectively promote the pace of digital twin development of large river basins. Taking Datang diversion channel in Sanshui District of Foshan City as an example, the three-dimensional real scene model of small watersheds was quickly constructed by using UAV tilt photography technology, and the three- dimensional real scene was published by GIS technology. Combined with video water level and flow monitoring, the short-term hydrological prediction model of small watersheds based on machine learning is integrated to realize regional water regime monitoring, forecasting and drill, providing a complete set of solutions for the development of digital twin small watersheds and the application of FEDE.