Abstract: In order to study the air-water spraying dust-settling affected by air supply pressure in underground coal mine,the Phase Doppler Interferometer (PDI) and dust concentration determinator were used to make a systematic measurement on the atomization characteristics and dust suppression efficiency for different air supply pressures based on the experimental system designed by the authors. The study results indicate that with the increase in air supply pressure,the air consumption shows an almost linear growth,and the water consumption decreases almost linearly. The particle size decreases with the increase of air supply pressure,and changes slightly when the air supply reaches a certain value. With the change of air supply pressure,both the average velocity and number density of droplet increase first and then decrease,and the liquid water content (LWC) reduces continuously. The efficiencies of reducing both total dust and respirable dust increase first and then decrease as the air supply pressure rises. The air supply pressure should not be too high and too low,the air supply pressure close to the water supply pressure should be selected,which can maintain the dust suppression efficiency of total dust and respirable dust.