Abstract: This paper proposes a method to study the internal flow field characteristics of air atomizing nozzles based on a simulation software. The effects of different gas pressures and different liquid flows on the velocity, turbulent kinetic energy and liquid volume fraction of the flow field in the nozzle are analyzed by CFD simulation software. The results show that the velocity and turbulent kinetic energy hardly change with the change of gas pressure or liquid flow rate when the radial cross-sectional area of the mixing chamber is constant, and the liquid volume fraction keeps a uniform decreasing trend. After the radial sectional area of the mixing chamber reduces, the velocity and turbulent kinetic energy are positively correlated with the gas pressure when the liquid flow is constant, and the increasing amplitude is larger. The volume fraction of the liquid decreases with the increase of gas pressure, and the decreasing amplitude also increases constantly. The binding force on the liquid gradually increases with the increase of gas force. When the gas pressure is constant, the velocity and turbulent kinetic energy increase with the increase of the liquid flow, but the increasing amplitude gradually decreases. The liquid volume fraction decreases with the increase of the liquid flow, but the decreasing amplitude also gradually diminishes.