In this study, spherical Ti-6Al-4V alloy powders were prepared by vacuum induction melting (VIGA-CC) in a water-cooled copper crucible and plasma rotating electrode (PREP). The void defects, argon content and hardness of Ti-6Al-4V alloy powders with different particle sizes were analyzed by means of SEM, synchrotron radiation CT scanning-three-dimensional reconstruction and argon content measurement. The experimental results show that the particle size distribution of VIGA-CC powder is between 40 and 180 microns. The particle size distribution of PREP powder is narrow, mainly between 110 and 180 microns. The VIGA-CC powders exhibited higher fraction of fine powders compared with PREP powders. The porosity, Ar content and pore size of metal powder increase with the increase of particle size, and the pore size of VIGA-CC powder is larger than PREP powders within the same particle size range. With decreasing the particle size, the cross-section structure of the powder becomes finer, and resulting in the increase of the hardness value. Overall hardness value of VIGA-CC powder is higher than that of PREP powder.