Abstract: A polyimide composite film for use in a flexible metal clad substrate, comprising: a polyimide base material film; a fluorine polymer layer, formed on at least one surface of the polyimide base material film, comprising polyimide resins and fluorine polymers, wherein the polyimide resin accounts for 2 to 20 wt % of the total solid content of the fluorine polymer layer, the aromatic functional group ratio of the polyimide resin in the fluorine polymer layer is greater than 35%, and the absorption onset wavelength (?onset) of the ultraviolet-visible spectrum is greater than 360 nm; a thickness ratio of the polyimide base material film to one layer of the fluorine polymer layers is 8:1 to 1:4; and a total thickness of the polyimide composite film is between 18 and 175 microns. Thus, the polyimide composite film has a low dielectric constant, low loss factor, and has good drilling processability.