The invention provides an acoustic wave dust removal device and a dust removal method thereof; a mixing device comprises a conical cone gas inlet part, a gas-liquid mixing barrel with the bottom for ventilation, a cover body for controlling a transmission direction of acoustic waves outside the gas-liquid mixing barrel, a modulation ring, an atomization spray nozzle for spraying atomized droplets into the gas-liquid mixing barrel, and a gas compression device arranged in the gas-liquid mixing barrel; the cover body is arranged at the top of the gas-liquid mixing barrel in a covering manner; the side wall of the top of the gas-liquid mixing barrel is provided with ventilation through holes; the peripheral edge of the modulation ring is provided with a plurality of bulges at intervals, the bulges protrude outwards in a radial direction, and the peripheral edges of the bulges and the inner wall of the gas-liquid mixing barrel form slits; the modulation ring can rotate around an axis in the gas-liquid mixing barrel, and when the modulation ring rotates in the gas-liquid mixing barrel, the acoustic waves are formed. The acoustic wave dust removal device and the dust removal method thereof are especially suitable for processing gas with higher PM2.5 content.