Co-ferrite thin films on Corning glass substrate have been fabricated by a chelating sol-gel process. Structural and magnetic properties of films have been studies as a function of annealing temperature with a X-ray diffraction and vibrating sample magnetometer. XRD result show most of Co-ferrite grains are oriented in randomly. Rapid annealing(RA)and Annealing processes were used for the variation of heat treatment and characteristic comparison. Coercivity were changed with thermal condition and magnetization were increased as a function of soaking time. With pronged soaking time, however, it was decreased due to the diffusion of cations from glass substrate by XPS analysis. RA process in preparation of Co-ferrite thin films was effective way to prevent inter-diffusion at interfaces and to form a single phase in reduced soaking time. And also YSZ(yttria stabilized zirconia)buffer layer between Co-ferrite and substrate was more effective to improve magnetic properties of the films at higher temperature. It was observed that Co-ferrite thin films have grain like feature typically 35nm size and their rms roughness is about 1.3nm. The saturation magnetization of the 900℃ 150 sec rapid annealed thin films was 400 emu/cm^3 and the coercivity of the film was about 3000 Oe.