Copper nitride (Cu₃N) thin films display typical trans-rhenium trioxide structures. They exhibit excellent physical properties, low cost, nontoxicity, and high stability under room temperature. However, they possess low-thermal decomposition temperature, and their lattice constant often changes significantly with prepared technologies or techniques, thereby enabling the transformation from insulators to semiconductors and even conductors. Moreover, Cu₃N thin films are becoming the new research hotspot of optical information storage devices, microelectronic semiconductor materials, and new energy materials. In this study, existing major prepared technologies of Cu₃N thin films are summarized. Influences of prepared technologies of Cu₃N thin films on crystal structure of films, as well as influences of prepared conditions and methods (e.g., nitrogen pressure, deposition power, substrate temperature, and element addition) on crystal structure and optical, electrical, and thermal properties of films were analyzed. The relationship between crystal structure and physical properties of Cu₃N thin films was explored. Finally, applications of Cu₃N thin films in photoelectricity, energy sources, nanometer devices, and other fields were discussed.