A composite optical film has the functions of brightness enhancement, self-diffusion and defect blocking. The film comprises: a structured substrate including a structured light incidence surface and a light emitting surface opposite the structured light incidence surface, wherein the structured light incidence surface includes longitudinal prism structures or longitudinal lens structures transversely arranged in rows; a support base plate adjacent to the light emitting surface of the structured substrate, the support base plate having a light incidence surface on one side and a light emitting surface on another side opposite the light incidence surface, wherein at least one of the light incidence surface and the light emitting surface has a plurality of buried particles, and at least one portions of the buried particles are protruded on the light emitting surface of the support base plate.