The invention relates to a high-heat-conductivity crosslinkable resin composition as well as a prepreg and a thermosetting copper-clad plate prepared thereby. The high-heat-conductivity crosslinkableresin composition is prepared by mixing crosslinkable matrix resin, modified resin, high-heat-conductivity filler, auxiliary filler, a flame retardant and an initiator through a ball-milling method. Anon-cured piece with uniform thickness and flat surface is prepared by extruding, mold-pressing or scrape-coating modes under the low-temperature environment, and the prepreg with proper toughness and viscosity is prepared through the steps of baking and the like. The thermosetting copper-clad plate is prepared by superposing the prepreg, a film and a copper foil through a laminating process. Thethermosetting copper-clad plate has an excellent dielectric property, mechanical strength, heat resistance, high heat-conducting coefficient, low thermal expansion coefficient and excellent propertyuniformity, and can meet various property requirements on the thermosetting copper-clad plate material by the current high-frequency and high-speed communication field. Good industrialized productionbasis and wide application prospect are achieved.