In this study, we fabricated spherical Ti-6Al-4V powders by gas atomization. High-resolutional synchrotron X-ray computed tomography (CT) and scanning electron microscopy were extensively performed to investigate the properties of the gas-atomized (GAed) Ti-6Al-4V powders. It is found that microstructure, porosity and argon gas content of the GAed powders are particle size dependent. The quantitative analysis shows that the porosity of powders rises from 0.05 +/- 0.04% to 1.14 +/- 0.11% when the particle size increases from 51.6 +/- 3.9 to 224.2 +/- 11.6 mu m, respectively. Certain amount of the atomizing argon gas is detected in the GAed powders. The argon content in powders also increases with increasing particle size, consistent with the porosity analysis. The results of three-dimensional reconstruction by synchrotron X-ray CT show that the pore number, pore size and porosity in the GAed powders gradually decrease with decreasing particle size. (C) 2018 Elsevier B.V. All rights reserved.