Abstract: At present, the coal mine grouting system was unable to meet the requirements of current coal mine safety production. Aiming at this problem, it studied a fire preventing and extinguishing system of fly ash dynamic pressure. This system used Omron PLC as the control core, consisted of the slurry pump, the sewage pump and the pressure transmitter etc. The auto decompressor controlled the motor starting of three-phase electric slurry pumps and the float ball liquid level switches controlled start and stop of the sewage pump. The pressure transmitter detected current pipeline pressure value, the value was transmitted into PLC and compared with set pressure value. If the pressure overloaded and sustained over 60s, it controlled the slurry pump stop. PC monitoring system received the real-time pressure and flow value from the PLC control system, then displayed, it realized the monitoring for the main pipeline pressure and flow of grouting system.