Ultra-fine powders of aluminum nitride were produced by non-transferred are plasma at atmospheric pressure. Chemical equilibrium compositions were calculated for various reaction systems. X-ray diffraction patterns of the powder synthesized in the cold-wall reactor were observed with weak peak intensity of aluminum nitride. It should be due to amorphous ALN as shown in FTIR spectra. Powder synthesized in the hot-wall reactor was observed with AIN crystal. In the high-temperature region, the degree of reaction was independent of NH3 gas injected. However, it was increased by injecting NH3 gas at the low-temperature region. Particle size was measured to be from 50 nm to 350 nm.