A thin-film capacitor core that has a core body, a covering film and a sprayed metal coating provided at two ends of the core body to form electrodes. The covering film is wound around an outer circumferential surface of the core body; the covering film has a base film and a waterproof layer attached to the base film. A waterproof covering process for the thin-film capacitor core can be performed by means of winding using a winding machine for producing a core body, such that on the premise of ensuring production efficiency of the thin-film capacitor core, the moisture resistance of the thin-film capacitor core is improved. A thin-film capacitor loaded with the thin-film capacitor core, and a printed circuit board loaded with the thin-film capacitor are also provided.