Copper nitride thin films were prepared by reactive radio frequency magnetron sputtering at different sputtering pressures with fixed nitrogen to argon ratio. The influences of sputtering pressure on the structure, optical band gap, and surface morphology of films were investigated. The results show that the preferential orientation of polycrystalline Cu3N thin films changes from [111] to [100] when the sputtering pressure increases. Meanwhile, the optical band gap (Eg) of Cu3N thin films increases with the sputtering pressure. The surface morphology of Cu3N thin film deposited at high sputtering pressure becomes smoother than that of Cu3N thin film deposited at low sputtering pressure.