Abstract The automatic control system of fire control is a water-supply system of a constant voltage. freguency conversion, PID of system transfer speed link for make pressure of pipeline keep in one pressure fluctating range and design. It’s some of execution of it that freguency conversion adjusts the speed systematically, when the pressure is smaller than above-mentioned ranges, the electrical machinery strengthens the power,thus increase the flow of the water pump,meet the systematic request. One the xontrary,reduce the flow. Key words: Automatic control system of fire control, Freguency conversion adjusts the speed systematically, Controller, Electromotor, Water pump