Based on thermodynamics and kinetics theory, a theoretical model to illuminate the process for preparing metal nanopowders by anodic arc discharging plasma method was set up, and the origin of plasma, metallic evaporation, the mechanism of particle nucleation and growth were investigated. The influences of various technology parameters on the properties of nanopowders by Anodic Arc Plasma were also discussed. In addition, the samples prepared by this method were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and the corresponding electron diffraction (ED) to determine the crystal structure, morphology, particle size and particle size distribution. The experimental results show that the crystal structure of the nanopowder sample is the same as the bulk material, being fcc structure, with an average size about 16 nm, distribution ranging from 10 nm to 40 nm. The technology parameters (such as the power supply, the pressure of gas, the arc current intensity, water-cooling condition, etc.) have great effect on the particle nucleation and growth, the particle size can be effectively controlled by varying the technological parameters.