Water is the main fire-fighting technology to extinguish Class A fires. But water also has obvious shortcomings, water mobility, most of the water sprayed into the fire will be lost, or because of the high temperature of the fire, the water has not reached the burning area has been vaporized, so that the cooling performance of water is not fully developed, for the fire area of large fire development is rapid and easy to re-ignite, the difficulty of fighting large fires, often can not be effectively put down in a timely manner. Add reagents in the water, or change the physical properties of water, increase the latent heat of vaporization, viscosity, wetting power, and adhesion, improve the effective oxygen barrier cooling capacity of water, extend the residence time of water in the burning area, reduce the flow resistance of water, increase the cooling and protection of water area, improve the application of water, you can give full play to the firefighting performance of water, reduce water consumption, improve firefighting efficiency. Especially in areas where water resources are lacking, some special areas (such as cargo ship fires, fire fighting water consumption will lead to capsizing) and some closed areas (generated by a large amount of steam dispersion is not effective, it will be possible to produce steam explosion expansion, resulting in rescue personnel casualties) to improve the efficiency of water fire fighting is of great significance. Add additives in water or change the physical properties of water to improve the fire extinguishing performance of water extinguishing agent called the water-based extinguishing agent.