The invention provides an in-situ preparation method of a cobalt oxide film electrode. The method mainly comprises steps of (1) carrying out cleaning, dust removal, rust removal and oil removal on a metallic nickel matrix so as to obtain a clean nickel surface; (2) through electroplate technology, electro-depositing a metal cobalt layer on the surface of the metallic nickel matrix; (3) configuringthe electrolyte solution used for in-situ preparation, wherein the solvent is de-ionized water and the main component of the solute is carbonate; (4) immersing the cleaned cobalt-plated electrode into the configured electrolyte solution, and carrying out continuous excitation on the surface of the electrode through auto-oxidation technology; and (5) taking out the electrode subjected to the reactions in the above steps, cleaning and drying the electrode and placing the electrode in a muffle furnace for heat processing for 2 hours of 150 DEG C - 500 DEG C, thereby acquiring the cobalt oxide film electrode. According to the invention, the technology is simple; the raw materials are simple; the method is easy to operate; production cost is low; and the prepared film electrode is good in conductivity, high in specific area, high in energy storage activity and suitable for industrialization mass production.