Dusty gas flow upward movement, liquid droplets the nozzle spray downward movement, dust particles liquid droplets through inertial collision, contact retention, dust due to humidification cohesion other mechanisms, so that the larger dust particles are captured by the liquid droplets. When the gas flow rate is small, the droplets with particles are sunk to the bottom of the tower due to gravity. The purified gas is discharged the top of the tower through the water purifier to remove the entrained fine droplets.