Metal/cobalt ferrite composite thin films with the saturation magnetization (M_s) of~580 emu/cm³ and the coercivity(H_c) of 1700 Oe were prepared by the reactive sputtering. With increasing substrate temperature, M_s of the thin films increased, while H_c of the thin films decrease. This sttributed to the precipitation of Co_xFe_1-x(x≈0.62) metal phase in the thin films. The metal phase showed the BCC structure (a₀=2.89 Å) and Im3m space group. Also, the cobalt ferrite phase was identified as CoFe₂O₄ with a cubic structure (a₀=8.39 Å) and a space group of Fd3m. For the higher cobalt content than the stoichiometric composition, Co_37.8Fe_62.2, the thin films with high M_s and H_c could be obtained in the wide substrate temperature range (200-40 ℃).