The electrolytic seawater sodium hypochlorite generator uses natural seawater and adopts high-speed electrolysis to prepare high-activity sodium hypochlorite solution on site. The sodium hypochlorite solution is transported to the dosing point as a biocide through dehydrogenation storage, effectively killing microorganisms, sea creatures, algae, and crustaceans in the water body, and preventing the blockage of circulating water pipelines and condenser systems.