Micro-fine spherical alumina (Al2O3) powders have been synthesized in this work with irregular feedstock materials by the SY119-30kW induction plasma sphroidization system. Effects of main operating parameters in fabrication process have been discussed and characteristics of the powders were investigated. The results show that the obtained powders with smooth surface exhibits fantastic sphericity, preferable density and better flowability. The purity of the fabricated powders has been improved and the phase compositions characterized by X-ray diffraction (XRD) shows the same results under different sheath gas (Ar or N2) conditions. Different axial positions of the injection probe strongly influenced the effectiveness of the treatment and Z=12.9cm would be the better choice for Al2O3 spheroidization in this experiment. The spheroidization efficiency of synthesized powders is almost 100% at feeding rate of 65g/min with the chamber pressure of 11.5psi (1atm=14.696psi), which decreases gradually as the feeding rate increases. The chamber pressure was also the vital factor that influenced the fabrication process and it should be coordinated with the carrier gas flow rate.