The working principle of water spray fire extinguishing system is that when the fire detector of the system detects a fire, it automatically or manually opens the rain alarm room group, and at the same time sends a fire alarm signal to the alarm controller to start the fire pump, so that the water can reach the water mist nozzle through the water supply pipe network. There are two main protection purposes of water spray fire extinguishing system, namely fire extinguishing and protective cooling, and its application scope is set according to different protection purposes. Water spray fire extinguishing system refers to a system consisting of water source, water supply equipment, pipeline, deluge valve group, filter and water mist nozzle. The fire extinguishing mechanism is that when water is sprayed on the surface of burning substances in the form of fine droplets, the comprehensive effects of surface cooling, suffocation, emulsification and dilution are produced to realize fire extinguishing. Water spray fire extinguishing system has the advantages of wide application range, which can not only improve the fire extinguishing efficiency of solid fires, but also be widely used to extinguish flammable liquid fires and electrical fires because of its characteristics of no splashing of liquid fires and good electrical insulation.