Abstract: The present invention relates to a composite material, a high-frequency circuit substrate made therefrom and making method thereof. The composite material comprises 20-70 parts by weight of thermosetting mixture, a fiberglass cloth, a powder filler, a flame retardant, and a cure initiator. The thermosetting mixture includes a resin containing vinyl in the amount of more than 60% composed of carbon and hydrogen with its molecular weight being less than 11000, and a solid styryl resin of middle or low molecular weight with unsaturated double bonds. The made high-frequency circuit substrate comprises a plurality of prepregs mutually overlapped, and copper foils respectively covered on both sides of overlapped prepregs. Each prepreg is made from the composite material. The composite material of the present invention enable to readily make prepregs.