Fe nano powders were synthesized by plasma arc discharge (PAD) process and studied by means of X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). Pure Fe rod($99.9\%$) was used as a source of metallic vapor under argon and hydrogen mixed atmosphere. The synthesized Fe nano powders had nearly spherical shapes and core-shell type structures. The influence of process parameters on the structure and size was investigated. The powder size increased with increasing of the chamber pressure and input current. High hydrogen gas ratio in chamber atmosphere affected the particle size and amount of Fe nanopowder.