Structure and magnetic properties of the as-deposited and post-annealed iron nitride films have been investigated systematically. A series of phases containing alpha-Fe, epsilon-Fe3N, xi-Fe2N and gamma ''-FeN were obtained as nitrogen flow rate (F-N2) increases from 0.5 to 30 sccm. An increase of the nitrogen concentration in the as-deposited films could be concluded from the phase transition with the increasing F-N2. After being annealed, some of the iron nitride phases are decomposed and gamma'-Fe4N appears in the films. The magnetic characteristics are dependent on F-N2, which can be ascribed to the facts that the nitrogen in the films turns the valence states of Fe into Fe+ or Fe-dipole with high magnetic momentum or ever H-like bond Fe+/dipole with low magnetic momentum based on the bond-band-barrier correlation mechanism. (C) 2011 Elsevier B.V. All rights reserved.