The utility model discloses an automatic gas-water spraying device for an underground cannon area, wherein a gas-water spray head and an acoustic-control electric switch are installed at the cannon area, the gas-water spray head is connected onto a dustproof water pipe and a pressure ventilation pipe, a water-supplying electromagnetic valve and a wind-supplying electromagnetic valve are respectively arranged on the dustproof water pipe and the pressure ventilation pipe, the dustproof water pipe is then communicated with a metering pump for providing a dust capturing agent, and the acoustic-control electric switch is electrically connected with the water-supplying electromagnetic valve, the wind-supplying electromagnetic valve and a metering-pump electric switch. During underground blasting, shock-wave acoustic-pressure signals generated by blasting are transferred to the acoustic-control electric switch, the acoustic-control electric switch is switched on to supply power for the metering-pump electric switch, the water-supplying electromagnetic valve and the wind-supplying electromagnetic valve, the metering pump works, the water-supplying electromagnetic valve and the wind-supplying electromagnetic valve are simultaneously turned on, and pressure wind and pressure water which contains the dust capturing agent are sprayed out of the gas-water spray head to form a gas-water mixture, so that the whole cross section of a laneway is closed to achieve the purpose of dust removal.