Water-based fire extinguisher is a physical fire extinguishing mechanism. Its fire extinguishing principle is physical fire extinguishing mechanism. The AFFF water-based film-forming foam extinguishing agent and the foam generated by nitrogen are sprayed on the fuel surface, and the water extracted from the foam forms a water film on the fuel surface, so that combustible substances are isolated from the air. The reagent forms and expands a thin water film on the surface of combustible materials, which isolates combustible materials from air and extinguishes flames. Spray water mist through the atomizing nozzle, the fire spreads, the heat evaporates, the fire temperature drops rapidly, and the oxygen concentration in the air in the combustion area decreases to prevent re-ignition. Water-based fire extinguisher is a kind of fire extinguisher used to extinguish the initial fire of combustible solid or water-insoluble liquid, but it is strictly forbidden to extinguish the fire of live equipment. It is an essential fire extinguisher for the development, processing, storage and transportation of wood, bamboo, fabric, paper and oil. It has the characteristics of convenient operation, high fire extinguishing efficiency, long validity period, re-ignition prevention and double fire extinguishing. This kind of fire extinguisher is environmentally friendly and can put out fires caused by ordinary household appliances.