The present invention discloses a thermosetting resin for expediting a thermosetting process. The thermosetting resin is composed of 100 parts of primary resin formed by mixing a brominized epoxy resin, a tetrafunctional epoxy resin and an epoxy resin with a high bromine content, and other materials including 35 parts of phenolic resin curing agent, 30 parts of tetrabromobisphenol A curing agent, 0.1 part of 2-ethyl-4-methylimidazole, 0.8 part Lewis acid, and 50˜70 parts of solvent, calculated based on every 100 parts of the primary resin by weight. The invention can expedite a thermosetting process and enhance the Tg of prepregs and clad laminates.