▎ 摘　　要

NOVELTY - Preparing composite thin film material comprises dispersing graphene oxide powder in solvent to obtain a graphene oxide dispersion liquid, mixing manganese salt powder and potassium permanganate aqueous solution into the graphene oxide dispersion liquid to obtain a mixed solution, coating the mixed solution on a substrate, then drying, to obtain graphene oxide/manganese dioxide composite thin film, carrying out reducing process of the obtained product to obtain reduced graphene oxide/manganese dioxide composite thin film. USE - The method is useful for preparing composite thin film material (claimed), which is useful in an electrochemical capacitor electrode of lithium ion battery for biosensor. ADVANTAGE - The method is capable of simply and economically preparing the composite thin film material in an eco-friendly manner with a high electrical conductivity and large specific surface area.