The utility model relates to a barrier film for preventing dampness degradation of a silicon-based detector fluorescent material. The barrier film comprises a bottom barrier film, an inner barrier film and a top barrier film which are laminated from bottom to top, wherein a fluorescent material is coated inside the inner barrier film; the bottom barrier film and the top barrier film are formed by alternately combining high/low-refractive index dielectric films; the inner barrier film is a high-refractive index dielectric film. A fluorescent layer is completely protected by the barrier film, moisture protection is realized, and the service life of the fluorescent material is obviously prolonged.