Pure and magnetic transition metal (TM = V, Cr, and Mn)-doped copper nitride (Cu3N) films with a preferred orientation of (100) were successfully prepared by reactive rf magnetron sputtering with an appropriate optical band gap for potential application in solar energy conversion. The incorporation of V or Mn can make the lattice constant smaller while it becomes larger after the inset of Cr into Cu3N. The calculated equilibrium structural parameters reveal that the unit cell of Cu3N could expand by inserting TM in the center or Cu vacancy of Cu3N. The SEM shows boundaries disappeared grains of V-doped sample, small spherical-like grains of Cr-doped sample, and greater glomerate crystal particles of Mn-doped Cu3N. The band gap becomes minor (1.50 to 1.22 eV) after doping with V or Cr and larger (1.50 to 1.56 eV) for Mn-doped samples, which realized the adjustable optical band gap of Cu3N films by doping with TM. What is more, TM in the center vacancy of Cu3N can improve magnetic properties more effectively than that of TM in the Cu vacancy of Cu3N. And Cr doping in the center gives the biggest magnetic moment of 0.2656 μB.