As a new type of nozzle, the internal mixing air atomizing nozzle has been widely used in the field of dust reduction via spraying. In this study, the effect of water supply pressure on the atomization characteristics and dust-reduction efficiency of the internal mixing air atomizing nozzle was investigated. Firstly, the FLUENT software was used to simulate the flow field inside and outside the nozzle under different water supply pressures. The numerical simulation results showed that as the water supply pressure increased, the internal pressure and water flow velocity in the mixing chamber of the nozzle increased while the air flow rate decreased sharply, resulting the continuous decrease in the relative velocity between gas and liquid. Meanwhile, as the water supply pressure increased, the fragmentation scale of the liquid jet at the outlet of the nozzle was prolonged and the atomization of the liquid was limited. Secondly, based on the custom-developed dust reduction experimental system via spraying, the atomization characteristics of the nozzle were investigated. According to the experimental results, when the water supply pressure increased, the water flow rate and air flow rate of the nozzle had exponential increase and decrease, respectively. As the water supply pressure increased, the range, droplet volume fraction, droplet size, and velocity all increased, while the atomization angle first increased and then decreased. Finally, the dust reduction experiment via spraying was performed under different water supply pressures. The results showed that with the increase of water supply pressure, the dust-reduction efficiency for both the total dust and the respirable dust first increased and then decreased. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.