Abstract: Algal blooms are a key factor threatening the water supply safety of large lake and reservoir water sources, making emergency treatment work crucial. This paper systematically summarizes the technical measures for emergency treatment of algal blooms in large lake and reservoir water sources, providing a reference for responding to algal blooms. These emergency treatment technologies mainly fall into four categories: physical, chemical, biological, and reservoir operation. Physical measures include mechanical harvesting, ultrasonic algae removal, flotation, and light shading for algae control, which cause no secondary pollution but have high costs. Chemical technologies involve chemical algicides and chemical flocculation, which take effect quickly but carry the risk of secondary pollution. Biological technologies include the application of microbial agents and the release of filter-feeding fish, which are ecologically friendly but have a slow effect. Reservoir operation technologies inhibit algal growth by regulating hydrological factors and are only applicable to reservoir-type water sources. Based on the differences in water body types of large lake and reservoir water sources, water intake areas are suitable for adopting safe physical treatment measures such as harvesting and filtration; lake and reservoir areas require large-scale operational measures such as aeration and ultrasonic treatment; bay areas are suitable for fast-acting measures such as flocculation and oxidation; and operation measures should be scientifically selected based on reservoir operation capacity and inflow conditions. Typical large lake and reservoir water sources such as Taihu Lake, Chaohu Lake, Three Gorges Reservoir, and Danjiangkou Reservoir have carried out emergency treatment of algal blooms, accumulating valuable experience in technical systems and disposal models. In the future, algal bloom treatment technologies will develop towards intelligence, greenization, and standardization, providing more reliable protection for water supply safety.