The invention relates to a method for preparing glue for producing high-speed copper-clad plates. The method comprises the following steps: blending and modifying barbituric acid with brominated bisphenol A epoxy resin and bismaleimide resin to prepare modified bismaleimide resin; forming a stable and uniform mixture from the modified bismaleimide resin by using butyrolactone as a solvent; and further adding other materials to prepare the glue specially used for producing high-speed copper-clad plates. The high-speed copper-clad plates prepared by the glue have low dielectric constant and dielectric loss factor, can meet other performance requirement of copper-clad plates, and are suitable for manufacture of high-speed printed circuit boards.