The present invention discloses an optical film and a cover plate for an electronic device. The optical film comprises: a support; a micro/nano-structure layer which is formed by providing a groove on a surface of the support, which groove forms a micro/nano-structure and is provided with a filler; wherein the micro/nanostructure layer has a visual gradient in at least one direction. The present invention provides an optical film, which realizes a visual change or a gradient effect, by adjusting the area ratio of the micro/nano-structure, the depth of the groove, the period of the micro/nano-structure or the density of the micro/nano-structure, and produces a decorative or practical effect. It plays an aesthetic role when used in the casing of an electronic device, and it can shade light but not block the sight line when used in buildings or automotive glass. Furthermore, no black spots will appear with this structure, and it is visually more artistic.