Fe-N gradient films and epitaxial Fe16N2 single-crystal films were prepared with a facing-target sputtering system. The Rutherford backscattering spectrum, x-ray diffraction, and selected area electron diffraction indicate that the gradient films possess some composition and structure gradient. The alpha "-Fe16N2, gamma’-Fe4N, epsilon-FexN(2], [011], and [001] directions can be observed distinctly by a rotational double tilting sample stand. By controlling N-2 partial pressure, substrate temperature, and crystal orientation, alpha "-Fe16N2 single-crystal films can be successfully grown epitaxially.