Abstract: Atomizing nozzle is the core component of the gas atomization process, which structural parameters, especially the melt tip taper angle of the delivery tube, have the great impact on the gas atomization results. Changing the taper angle of melt tip is more effective and economical than changing the atomization process parameters such as gas pressure and temperature. The computational fluid dynamics (CFD) method was used to simulate the internal flow field in the spray chamber with different melt tip taper angles in this paper. The commercial CFD software FLUENT was used to calculate and visualize the complex multiphase flow process in the closed spray chamber with high temperature and high pressure. The influence of various factors on the melt breaking effect in the single phase flow field was analyzed, and the volume of fluid (VOF) model was used to simulate the primary atomization process. The results show that the direction of air flow can be changed by changing the melt tip taper angle (16°, 22°, 28°, 34°, 40°, and 46°). With the change of taper angle, the stagnation point position, stagnation pressure, and suction pressure show the regular characteristics in single-phase flow field. The mass median diameter (MMD) of the primary atomization also varies with the change of melt tip taper angle. The droplet size distribution after primary atomization can be controlled by changing the melt tip taper angle. The minimum MMD is 304 μm when the melt tip taper angle is 34°.