The present disclosure provides a method for modifying a polyphenylene ether resin, a laminated film composite, a laminated film, and a substrate. The method for modifying a polyphenylene ether resin using an indene oligomer to reduce the molecular weight of the polyphenylene ether to obtain an indene oligomer-modified polyphenylene ether resin. The modified polyphenylene ether with a smaller molecular weight has a lower softening point and melting point, a better interfacial adhesion, and can be better adhered to a substrate of an integrated circuit. Meanwhile, because it has a lower dielectric constant and dielectric loss, the dielectric constant and dielectric loss of the substrate can be reduced, thereby solving the technical problem of electric leakage and heat generation caused when the existing polyphenylene ether resin is applied to an integrated circuit when the feature size of the integrated circuit is reduced.