The formation of Fe nanopowders by Plasma Arc discharge process and sintering behavior of Fe nanopowder has been investigated. The effect of processing parameters on the size and microstructure and their pressureless sintering behaviors have been analyzed. Also the addition effect of micron powder to nanopowder on the compaction and sintering was studied. The prepared Fe nanpowder showed nearly spherical shape with the average size of 100 nm. The surface oxide layer of nanopowder played an important role on the initial densification of the green compact. The hardness and sintered density of nano/micron bimodal powder was similar to those of pure nanopowder.