High-purity aluminum nitride nanopowder was synthesized using the RF induction thermal plasma technique. The nitrogen gas flow rate, plasma power and reactor pressure were controlled to increase the conversion rate of Al powder to AlN nanoparticles. The compositions of the obtained powders were investigated through XRD and EDS analysis. The synthesized aluminum nitride nanoparticles included polygonal and rod-shaped nanoparticles and ultra-fine particles below 10 nm. The particle sizes generally ranged from 20–60 nm in TEM analysis. The specific surface area, band structure and impurities of aluminum nitride nanoparticles were also evaluated by BET, FTIR and ICP-OES analysis.