A high thermal conductivity prepreg is provided. The high thermal conductivity prepreg includes a high thermal conductivity reinforcing material and a dielectric material layer formed on the surface of the high thermal conductivity reinforcing material, wherein the high thermal conductivity reinforcing material is prepared by a process which includes the following steps: (a) providing a precursor aqueous solution, the precursor aqueous solution includes a precursor selected from the group of organic salts, inorganic salts, and combinations thereof; (b) subjecting the precursor aqueous solution to a hydrolysis reaction to form an intermediate product aqueous solution; (c) subjecting the intermediate product aqueous solution to a condensation polymerization reaction to form a pretreatment solution; (d) impregnating a reinforcing material with the pretreatment solution; and (e) oven-drying the impregnated reinforcing material to obtain the high thermal conductivity reinforcing material.