Abstract: Inconel 625 metal powders used for 3D printing were prepared by vacuum inert gas atomization (VIGA), using the independently developed and designed tightly coupled gas atomization device. By adjusting the atomization parameters, the effects of the inner diameter of delivery tubes on the particle size distribution, surface morphology, oxygen content (mass fraction), and flowability of the metal powders were investigated. The results show that, the high quality Inconel 625 metal powders can be obtained by the tightly coupled gas atomization device, showing a wide range of particle size distribution and a high powder yield with good sphericity and fewer satellite spheres, the yield of the metal powders smaller than 53 μm can reach more than 50%. With the increase in the inner diameter of the delivery tubes, the yield of the metal powders reduces, and the oxygen content (mass fraction) decreases obviously. The prepared metal powders used in the different 3D printing devices can meet the performance requirements for the powder materials.