Ultrafime powders of aluminum nitride were produced by a dc plasma jet. The evaporation process of the aluminum and the mechanism of the A1N synthesis were then studied. A1 bulk and A1 powder were used as raw materials. The cylinder type A1 bulk was rapidly vaporized by an argon-nitrogen mixing plasma. As a result, ultrafine powders of A1N were prepared by the reaction of A1 vapor with ambient ammonia gas. It was also observed that the conversion of A1 into A1N was mainly affected by the injecting position and flow rate of the NH₃ gas. When using A1 powder as the raw material, crystalline A1N was obtained on the hot wall reactor, whereas gas needs to be injected at a lower temperature because NH₃ gas can easily be dissociated into molecular nitrogen and hydrogen at a higher temperature region. The powders observed were fluffy, white-colored with diameters ranging from 10 nm to 300 nm.